What is the right amount of evil?
This Mouse was even more ruinous than I thought...
Last Saturday I streamed* a playthrough of my JRPG Project "Leid vom Meeresfall".
About 30 minutes in or so, I noticed how my entire party had something around -24,000 XP, which very much confused me. I was pretty sure it had something to do with getting killed by the Killer Mouse and the Bonus XP system I had in place, that gives a character additional XP, if they get killed in Battle. The amount of bonus XP is based on the last damage they took, however there is a cap in place, that limits it to a maximum of 100 * their current level. I specifically put that limit in place, because of the Killer Mouse, but then somehow it not only didn't trigger, it also subtracted the XP, instead of adding it.
It was a bit later, while I was explaining something else to Eve, who graciously agreed to sit in with me while I did the Stream, where she figured out what went wrong. It turned out that actually getting put into 12 Levels worth of negative XP was the system working as intended, I just forgot some of my own strange decisions.
To make sense of it all, let me talk to you about the nature of damage and healing in this game:
What happens when a character takes damage in an RPG?
Usually their HP gets reduced by the amount of damage they took.
In mathematical terms you have something like this:
new_hp= current_hp-(enemy_damage)
What happens mathematically, if the damage they were taking was actually a negative number?
enemy_damage=enemy_damage*-1
new_hp= current_hp-(-enemy_damage)
Since subtracting a negative number causes it to be additive, we're suddenly increasing our hp, instead of decreasing it.
In this sense, "Healing" can be considered to be "negative damage".
Don't ask me how and why I ended up going down this particular path somewhere back in July of 2025, but this thought of "Healing is just negative damage" somehow amused me so much that I decided that this how I wanted to do "healing" for this game. Basically it would use the same damage formula and calculation, but the value itself would be negative and thus lead to an increase in HP.
Obviously treating healing as a specific damage type now also meant that it had to have its own defensive stat associated with it. I then realized that this idea of "healing defense" paired very nicely with my other plans of giving party members the ability to "help" each other. Because what else could it mean, if someone were to be resistant to healing than them refusing to let others get close to them?
If you've played the current build of this game and were confused by the "Soul Defense" value during battles, this is where it's coming from. Soul Defense is a shield that "protects" the person who has it from the influence of others. This means healing and helping, but it also protects them against status effects at large.
Now if we have healing as a damage type and its own defense, what would it mean if someone were to attack with "positive" healing damage?
Instead of increasing HP, it would decrease it AND since most things in this game don't have Soul Defense, it pretty much bypasses any and all resistances.
However, because the game generates a healing effect by turning a positive number (the actor's damage value) into a negative number by multiplying it with -1, we need to feed it a damage number that is already negative, so that it gets turned into a positive number instead.
You might start to see what went wrong here. The Killer Mouse's "Mouse Kill" Attack does Healing damage and so it has to feed a negative number into the damage formula. For unrelated reasons, the bonus XP for being killed gets calculated before that actual damage is applied, which means that in this specific case, it's set to a negative number. Because the number is negative, it then doesn't get caught by the "hey check if the bonus XP is higher than the level cap" conditional, causing it to then put the entire party into a deep XP deficit.
There are several things that I love about this:
- This entire thing, while not being intended, is the result of the existing systems working as intended. In a sense, the players are being killed by a negative number, so obvioulsy the bonus XP should be negative. It's just that I completely forgot about that part when I had the idea to give characters additional XP when they die.
- The reason the "Killer Mouse" exists is because I immediately wanted to put a day-ruining rodent into this game, and without knowing I actually made it even more ruinous than I thought.
- I purely ran into this problem, because I wanted to show off a different thing during that fight for the Stream.
- It is my goal for this game to turn into a gigantic systemic mess where things happen that make perfect sense, but that I have not planned for at all.
- It gave me more stuff to play with!
Obviously, while I'm a big proponent of Evil Games, I do think that putting players into -24,000 XP debt 20 minutes into the game is a bit mean**. However, this entire sequence is the result of the game's systems just working as they were built, and I'm also very committed to letting my system's "do their thing" after I set them up.
I want to treat the systems of this game as almost metaphysical elements. They set the rules and possibilities of the world the game takes place in. So when getting killed by Healing causes you to lose XP, then this is just how this world operates.
I did what I felt is the most sensible thing: While it's still possible to get into negative XP and while getting killed by healing still gives you negative bonus-XP, the latter is now capped at the same value as the positive bonus-XP is. This way you're not immediately in a situation where you would have to play through over a third of the game, before you're actually able to level up again.
In regards to being in negative XP, I now added a modifier that increases a character's stats, based on the amount of XP debt they have accumulated. Considering that, especially as the game goes on, it will be harder and harder to actually get into negative XP, this stat boost will mostly be useful and easily available very early on.
Also, it's already possible to have negative items and negative MP, so why not also allow negative XP?
The fun thing with Leid vom Meeresfall is that you can't really die. Losing a battle still removes the encounter from the map and allows you to progress.
However, whereas a game over, or a reset to a previous checkpoint wipes the slate clean of your mistakes, in this game you have to live with them. I had a truly horrible time during that Stream, because I kept dying in battle, which caused characters to get more and more "wounds", which altered how they behaved. Add to that the fact that I couldn't really get any stronger through fights and that I refused to return to a checkpoint to heal up, and things just kept getting worse and worse.
However, it was also all because of my own decisions and at some point I did manage to get to a new checkpoint and rid myself of most of my problems.
I guess this is where this again swings back to Evil Game Design:
It is not about being actively hostile and antagonistic to the players. It's about allowing them to make mistakes and exist within them.
In situations like these, I always think the best way of dealing with them is to address them directly and do something with them, instead of just closing them off. That doesn't mean that the way of addressing the issue is always in the player's best interest. While the stat boost from being in negative XP is actually quite significant, you also lose it gradually while not being able to level up. So unless you find a way to put yourself into monumental XP debt right at the beginning of the game, you will still end up in an unpleasant situation. It's just delayed for a bit.
The Killer Mouse is there to make things worse for you, but it also only shows up when very specific conditions are fulfilled and even then, it will not immediately kill you. No, you have to actively want to have your day ruined by it, and if that's what you want, then why should I prevent that from happening?
If you're curious, the current build of the game that's on itch still has the -24k XP debt in it. I will probably patch it out later this week, so maybe give it a go yourself.
*Unfortunately I very much messed up the audio balancing on the stream and only caught it afterwards, so while you can watch it, you're going to have a hard to to listen to anything that Eve said during it.
**this doesn't mean that I didn't consider it! Dungeon Encounters after all does let you get into money debt very early on and doesn't put any breaks on that at all.