There’s a lot of hidden math in the Resident Evil 3 remake. From Jill’s health meter to what benefit you’re actually getting out of your weapon mods, you end up having to take a lot on faith in this game.

Fans have developed tools that let them peek under the hood of the PC version of the game, however, and as it turns out, Resident Evil 3 has a lot of interesting hidden systems, many of which have to do with what benefits you actually get from Shop items and weapon mods. Let’s take a look.

What the Various Upgrades and Mods Actually Do in Resident Evil 3

The PC version of RE3 already has a couple of fan-created hacks, like new costumes for Jill or model replacements. However, it’s also got some mods that are meant to help out speed-runners, some of which you may have seen streamers like Carcinogen or Bawkbasoup using already.

With the RE3 Speed-Run Tool (SRT), a player can dig into the game’s math and find out the actual numbers that RE3 is running on. This is a big time-saver for people who are trying to optimize their routes through the game and set world-record speed runs, as they can figure out exactly how RE3’s various invisible systems work.

Even with the SRT, though, it’s an imperfect process. Fans have gone out of their way to dig through the numbers, though, and what they’ve figured out can be eye-opening.

First off, both Jill and Carlos have a flat 1,200 HP. This doesn’t change between difficulties, and means they’re both actually very tanky compared to Leon and Claire in last year’s Resident Evil 2 remake.

If you pick up a Recovery Coin from the in-game Bonus Shop and keep it in your inventory, you automatically start to heal for 16 health per second once you’ve managed to keep from taking damage for a total of 22 seconds. This can restore you to full health. Carrying 2 Recovery Coins doubles the amount that you heal per second, but doesn’t affect the time it takes for that healing to kick in.

If you carry both of the Defense Coins, it appears that the benefit they grant is actually higher on the tougher difficulties. Having two Defense Coins in your inventory on Assisted difficulty is worth 50% damage reduction, but it shoots up to as high as 70% (!) on Nightmare or Inferno.

Numbers like precise incoming damage are hard to come by, though, because of RE3’s adaptive difficulty system. Like several other mainline Resident Evil games, RE3 actually keeps track of how well you’re doing, and will adjust its damage numbers on the fly to make sure you’re still being faced with a challenge.

Fans have tested this system with the SRT, and have determined that the Difficulty Adjustment (DA) can go up and down as you play. Shooting an enemy or executing a perfect dodge raises your DA; taking damage from an enemy attack or continuing from a checkpoint lowers it. At low DA ranks, you inflict more damage with your successful attacks and take less damage when you’re hit, but as your DA rises, enemies get a significant damage boost and you inflict slightly less damage on them in turn.

You can see the RE3 SRT running in the bottom right corner of the screen during this world record by speedrunner Distortion2. Note how it’s tracking the DA, Jill’s actual health numbers, and other useful information as he plays.

There are roughly 19 ranks of difficulty adjustment in RE3. At Rank 0, a single zombie bite inflicts 133 base damage; at Rank 18 or 19, that damage spikes to 684, or over half of Jill or Carlos’s health total.

Like a few other Resident Evil games, RE3 handles its base difficulty setting by manipulating its starting rank. If you play on Assisted, you start on a manageable Rank 2, and no matter how poorly you perform, you can’t get higher than just below Rank 4. Standard starts at Rank 3 and can go as high as 8, while Hardcore begins at 8 and has a maximum of 9.

Nightmare difficulty, much like Professional mode in RE4, just pegs you at Rank 10 for the entirety of the game, regardless of your performance; Rank 10 also represents a strange mathematical breakpoint for the game where you both take and deal more damage, making it the “Dante Must Die” option of RE3.

The final difficulty, Inferno, begins at Rank 11, and can go as high as Rank 19 if you’re still wiping the floor with it.

A side effect of the adaptive difficulty is that it’s hard to pull precise numbers out of RE3, because it’s got a lot of invisible factors that govern things like damage output. Monsters are also hand-placed with varying health totals throughout the game, much as they were in last year’s RE2 remake. Some may be much stronger or weaker depending on the circumstances, and many appear to have specific hard-coded vulnerabilities.

For example, the Nemesis has roughly 8,000 health during the sections near the start of the game where he’s pursuing you. A hand grenade typically does just under 2,000 damage to anything within its explosive radius. That isn’t enough to stagger Nemesis on paper, but a single hand grenade will knock him to his knees regardless, just as if you depleted his health with another weapon. In fact, if you’re trying to knock him over to steal his Supply Cases, a single hand grenade is always going to be your most expedient option.

Likewise, standard explosive rounds from your grenade launcher do relatively little damage to Nemesis, around 200 HP, but will almost always drop standard zombies in one shot. Nemesis does seem hard-coded to eat a brief stun whenever you bounce an explosive round off his stupid face, so they’re still useful at times, but they don’t do a lot of actual damage; meanwhile, zombies all seem to have some kind of hidden damage multiplier that kicks in whenever you use explosives on them. Parasite zombies, on the other hand, do not care about grenades at all, and shrug off just about any damage that isn’t directly against the eye in the middle of their parasite. 

One of the biggest takeaways from SRT testing, to my mind, is how grenade rounds work. Speed-runners on last year’s RE2 proved early on that the real benefit of weapons like the grenade launcher wasn’t simply in exploiting weak points, but in how flame and acid rounds had a lot of their impact back-loaded into a damage-over-time effect.

The same goes for RE3. Flame rounds are incredibly effective against Nemesis, but if you’re simply dropping them on him one after another until the cylinder’s empty, it turns out that you’re leaving a lot of damage on the table. If you hit a target with a flame round, it gets set ablaze, and will burn for around 100 damage a second for the next seven seconds; if you hit with a second flame round in that period, you reset the clock on the fire damage but don’t stack it. You’re better off hitting a target like Nemesis with one flame round, then letting him burn for a few seconds while you switch weapons.

For such a short game, there’s a lot to dig out of Resident Evil 3, especially as the competition for the shortest possible speed runs begins to heat up. Check out some of our other guides on the subject:

• Complete the Re: Master of Unlocking Record
• A video guide to getting the Electric Slide achievement
• How to solve the vaccine temperature puzzle

These damage and health numbers for RE3 are mostly guesses by the fans, gathered by use of a third-party tool, so you shouldn’t take them as gospel. It does help to indicate why certain strategies are being used now, by speed runners and completionists, and should provide some useful insight into what you’ll see whenever RE3 inevitably shows up at Games Done Quick in August. Be sure to check in with us at Twitter, @PrimaGames, for more tips and tricks.