I think you need to consider this at a more fundamental level: what is the gameplay purpose of having a health system in your game?

A conventional health system serves two purposes: (1) it gives a staged failure state to combat, and (2) it serves to create long term resource management with health between fights.

You say you want your game to be exploration heavy. Why is health and death part of your game at all? Is it just there to add challenge? How does the player losing health and then dying in combat support this goal? Does carrying injury from one combat to another support your goals for your game? If not, why use a conventional health system at all? Why not, just for example, have an indestructible character and make the challenge finding a way to get past enemies at all? Why not have being hit cost you some resource, like gold, instead of being a countdown to death?

In order to give a thoughtful design answer to how healing should work you first need to know why the player is healing at all.

You mentioned having thought about auto-regeneration and your issue with that was the possibility of a player, while in the middle of a fight, running around while they auto-regenerate health.

Have you considered auto-regeneration only when not-in-combat (aka out-of-combat)? This is an approach taken in many games.

You could combine this with one or more of your other ideas for a way for players to heal while in-combat.

You also mentioned having thought about using healing items, but not wanting the player to feel discouraged from using them, for fear of running out of healing items and having to go collect more.

What if you combined this approach with one of an infinite-use heal? For example, an unlimited-use item that heals a small amount of health, in addition to a limited-use item that heals a large amount of health.

Another approach could be a healing skill/item that can be used over and over, but with a cooldown (or some other cost, such as mana). That way, the player would be able to regularly use their healing skill (when strategically applicable).

You could have auto-regeneration, but discourage players from waiting for it all the time by making it very slow regeneration. Then have other healing methods that encourage or promote the way you'd like the player to play (like the idea to heal when you hit an enemy)

There's lots of examples out there in 2D platforming, it's really a question of how you want healing to be "interesting"? I would agree with suggestions that "skillful" play should be rewarded, but also give the player enough opportunities to use resources and play strategically.

A few thoughts:

• DeadCells uses a "flask" system where you fill up between levels (or healing station in your case) and can then heal a limited number of times using it. It also requires the player to stand still for a few seconds, making it tricky (not impossible) to use during combat.




• Mario. You gain "health" (and abilities) by getting power ups. Getting hit loses these abilities/power ups, instead of you dying immediately.




• Health steal/vampire. Kinda interesting, if your theme is right for it. But you've got to balance the game on the premise that you hit a lot more than you get hit, e.g. that 'slow, tanky' bosses become relatively easier.




• You could look at making healing a limited resource that costs you something (e.g. points, gold, items whatever)




• Some kind of special heal attack that is relatively difficult to hit with (long wind-up), and causes player to be vulnerable if they miss (long wind-down). It has a reasonable cooldown and/or cost. Heal amount is dependent on the health/difficulty of the opponent hit. Could be a nice balance of risk/reward. (i.e. I'm on low health, do I risk trying to land my heal on the boss?)

Limit healing resources and put any additional resources into new, unexplored areas. Create the incentive where if a player wants to heal, they have to press on into more of the map.

You can do this a few ways:

1. 
   

   Have physical healing locations on the map, but cap the health they restore. Many games (like Metroid) have healing rooms, but they provide unlimited health, encouraging the player to backtrack when in danger. Instead, make them limited use.

   
   
   

   For example, in Moonlighter, each floor of the dungeon has a healing pond that restores a set amount of HP. Once this limit is hit, the pond is "used up" and no longer heals. The cap is also relatively low (a little less than the player's max HP)

   
   
   

   The pond on each floor has to be found in the first place (encouraging exploration) and when emptied, the player has to risk exploring the next (more difficult) floor if they want additional healing.

   
   


2. 
   

   Another option is to limit the number of healing items that exist in the game and hide them. This is often seen in survival horror games (I'm specifically thinking of Resident Evil 4 or the first Dead Space).

   
   
   

   This creates tension, as healing becomes high risk (health right now may mean less health later). The drawback of this approach is it can make a player avoid risk or combat. Survival horror games address this by making combat unavoidable (which, from an earlier comment, sounds like you are open to).

   
   
   

   Another strategy you can use is letting the player know that there will be more items in the next area. Tell them that, for example, "Each level has X healing talismans" (can be explicit dialog or a "You found X/X items" on the map screen).

   
   
   

   This way, they know that healing is limited and in order to heal, they have to explore. Also, if they want to heal more, they have to defeat the boss and move on to the next area.

   
   



3. Lastly, you could figure out a way to tie health directly into progression, for example, every 1% of the map filled gives the player 1% health. Obviously, this needs more fleshing out (like, what happens after the player explores 100% of the map?), but if you figure out a mechanic where the only way to heal is to move forward, that would alleviate many of your concerns.

I hope this helped, good luck with your game!

If cowarding during a boss fight is your major problem with auto-regeneration, make the auto-regeneration non-linear: give it a cap of auto-regeneration, and disable it during boss fight (boss fight only, not normal combat).

During normal exploration, make the auto-regeneration fast when your player is in low HP, and it gradually gets slower when HP regenerates (regen_speed = 1/HP). Such a system will make your player keep their HP not to low (hence the purpose of healing), but also not too high (higher HP, lower regen_speed).

If the player is patient enough, or if your dynamic-healing-system is not set correctly, waiting can still be an option. To prevent this, set a max cap for auto-regeneration. For example, auto-regeneration speed is 0/second over 50% HP. You can still heal with potion, health stealing, spells etc. to go beyond 50% HP, but not auto-regeneration.

Lastly, give the boss an aura that disable the auto-regeneration. If it's frustrating for players to start the boss fight with low HP, then give the boss an aura that "heals you to full health, but disable the auto-regeneration", or even with "heals you to full health, disable auto-regen, and revert your HP after the boss fight to pre-boss-fight level".

An explanation for the last aura could be: the boss is fighting your player in the "soul realm", and thus

• your soul HP is irrelevant with your character HP, and always starts with 100%


• unlike physical body, soul don't heal themselves


• after the fight, your soul goes back to the character, and hence your (character) HP will be the same level pre-fight

Doom (2016) actually has a great example of rewarding interesting gameplay with healing through its glory kill system. By rewarding the player with health for getting close to finish off demons, it was able to create a gritty fast-paced in-your-face adrenaline shooter in stark contrast to the cover-based shooters that dominate the market. You could do this same sort of thing, but rewarding the kind of gameplay relevant to your game

If your goal is to drive exploration and platforming, work with that. Create healing triggers based on those types of behaviors. Maybe every time you enter a room you've never been in before, recover something like 25% of your health (or 100% when entering a boss room). Perhaps even have healing for killing an enemy for the first time. You could also put a few frames of invincibility at the beginning of jumps and add a small amount of healing if you get hit within this window (perfect dodge healing).

Missed the timeframe by the looks of it, but will still complete my answer:

Associate self-healing in-combat mainly with the player performing combos. It could be combos that the players are taught or that they are subtly hinted at, through messages of general explanation or by suggesting the combo for a particular situation.

Considering the fact that you want to find a way for gaining health and mana, performing combos could cost mana, but heal you and in order to gain mana the player has to be accurate with their combos. This would also provide a relatively sustainable approach for a player that seems to be always 'in combat', since everything they would need to succeed is all about their skill.

You can always tweak the numbers by:

- making harder combos heal for more

- having higher accuracy on landing combos gives you more mana

- adding synergy between weapons and health/mana (such that if you have a weapon that has Combo Power +10 would give 10% more healing and more mana from combos, or Healing Power +10 only 10% more healing.

- since I saw classes mentioned, you could also have class synergies where, I don't know a Druid gains more Healh innately but has weaker damage to compensate, or a Mage gets more mana out of combos, Archer would have more accuracy on combos, and so on... (Just examples, I know it might be far from your game world.)

This would allow to have levels of difficulty and would mean that, at times, players (and/or their classes) would need some item/strategy in approaching an enemy. It would also require that players get a grasp of the synergies and the advantages and disadvantages of items/classes/combos. You also get to have a more developed world if you wish :)

There's been an isometric (like Fallout 1&2) 'Fallout 76'-like fan made free game available for the last eight years, called Fonline (F-Online; Fallout Online). All you need are the copyrighted data files from F2.

It has a more or less open world, where in instanced encounters you can usually find the two things you need to craft healing powder : a broc flower and a xander root. Maximum carry weight and the time it would take to make too many, prevents abuse and getting stuck because something is too hard.

The flowers and roots aren't hard to find like in Fallout3, you just grind as many as you need until that gets boring and you think you can handle it. All the while, real people and NPCs can come kill you and take all your stuff, but at least you get a little XP for crafting things.

Healing level interest: 9/10.

Agency: 11/10. Because there are several ways to heal yourself; the better ones come at the cost of sacrificing points into non-combat skills such as First Aid, or the ability to craft stimpaks (which require points in Science, a blueprint, and having paid to learn the Chemist profession).

Healing Powder is pretty much useless in combat for even mid-level characters; it's what you use afterwards because they're free.

For a 2D platformer, you need to make (procedurally generated?) places where they can grind what they need if they have to. Otherwise you just die or run back to the save spot like in Castlevania SotN.

If I died because I ran out of powders, that's my fault.... Agency.

Have your character eat or drink to heal. Although they can use it unlimited times, you can limit it behind a long use-time—that is, they are required to stand still for 5+ seconds to heal. Have the item only heal 10%-25% means they have to use it multiple times. This would encourage exploring.

As for bosses. Providing an area to "catch-your-breath" before you start the fight would allow them to heal up before fights. Bosses could have "quick interrupt" abilities that they use when you try to heal, thus preventing you from cowering/hiding, while some bosses would have long animations or routines, thus making healing a possible strategy in those "windows" (or dealing a little extra damage).

Maybe have artifacts or relics that the hero can switch between that provide different healing benefits. Such as passive health regen, consumption healing (food), life-steal, etc. Thus, the player can decide which they prefer to play with.

Dual hit point system

Pillar of Eternity has an interesting approach to it, having two types of hit points, which may help you or give some ideas:

Endurance

Whenever a combat starts, this is a character's hit points for the duration of the combat. It quickly regenerates outside of combat. When the character drops to 0, it is incapacitated for the rest of the fight (other characters can still fight, alternatively it could also mean death for single characters). When a character takes damage, it drains both, Endurance and Health. Healing only affects Endurance and is therefore only relevant in combat.

Health

This is the long term hit points characters have. It is a multitude of Endurance, and the given Endurance in a combat can not exceed the remaining Health of a character. When Health drops to 0, a character dies. Resources have to be used/sacrificed to restore this, and it does not regenerate. Also there are interactions with abilities, like restoring Endurance in a fight, but not Health.

Now as an example, you can have a warrior with 20 maximum Endurance and 100 maximum Health. You go around, fight enemies, lose Health from combat to combat. The benefit is this: The character has something long-term to handle while progressing through the game, which can be more slow and difficult to maintain - but the immediate combat hit points are not drastically low or high in order to balance it.

Possible variations:

• Endurance scales with the relative amount of current Health. Meaning as Health drops from fight to fight, the character becomes weaker as well in combat, either by starting with less Endurance or suffering less power.


• Similar to Overwatch, an additional layer of hit points could be added, like Armor. Meaning you can allow your character to take some damage in each combat without draining Health.


• Another version is Endurance which regenerates in a moderate pace in combat, where Health does not. Effectively it would mean the player must take care not to take too much damage in a too short time-span, but also consider that he won't regenerate hit points forever.


• Another honorable mention is World of Warships, where only a part of damage taken can be repaired - be it the last 'n' amount of damage or n% of total damage taken. In essence this is also a dual hit point system. Variance can be had in damage types, meaning some may be better at preventing repair at the cost of other factors.

Another idea:

You generate mana through movement.
You can spend mana (via a button) to heal.
However, while healing, you move at a slower pace (risk enemies catching up) and cannot jump (limited mobility).

Pretty much along the lines of the answer @CertainlyNot provided:

Have you ever played Quest64? You regain magic points by moving around in the world, and striking enemies with melee attacks. You obtain limited amounts of healing items, and a majority of the healing in the later parts of the game in between (or during) fights will come from healing spells. Due to the random encounter system in the game, there's an interesting risk-reward to saving mana for fights, or spending it as you gain it to heal up. Perhaps something like this is what you're looking for.