Vaccine is a Retraux Survival Horror video game with Roguelike elements heavily inspired by the first Resident Evil from 1996. The game was released on February 21st, 2017, and developed by RNC (Rainy Night Creations, aka solo developer Alfrido Abejon Garcia).
Besides PS1-era graphics, tank controls, and fixed camera angles in the style of classic survival horror games, Vaccine also has procedurally generated Randomly Generated Levels and character leveling. Players take the role of one of two special operations police officers who are sent to investigate a mansion and find themselves trapped inside. When one of the officers becomes infected, it falls upon the other to find the vaccine and save their partner.
A Video Game Remake of the game, Vaccine Rebirth, made on a newer version of Unity, was released on May 25th, 2023. The rooms have been completely redone and are slightly more coherent, the gameplay and combat is slightly less indiejank, item placement is more obvious and you have less issues with key items blending into the background, and some quality of life improvements have been added such as an in-game map and a document viewer, but overall it looks and plays similar to the original game, with the same plot and ultimate objective.
Vaccine and Vaccine Rebirth contains examples of:
- The '90s: Rebirth establishes that the games take place in 1998, in the same time period as the first Resident Evil from which it draw inspiration.
- Apocalyptic Log: Notes from researchers who were researching wormholes and created the dimensional displacement can be found throughout the mansion.
- Checkpoint Starvation: The entire game has to be beaten in one go, as there is no saving. Getting the "true" ending requires a minimum of 3 loops and takes almost an hour.
- Elite Zombie:
- In the original game, the reptilian-like crawlers are extremely dangerous, and once alerted are capable of outright killing you with nothing you can do about it if you're only armed with a knife. You need to take them out with either firearms, proximity mines, or use a repellent so they won't attack you then knife them to death.
- In Rebirth, the crawlers are much less dangerous, but the final loop has large, tough treeman-like monsters and fast, Hunter-like gorilla monsters which can only safely be fought with firearms, mines, or repellent.
- Evil Doppelgänger: One of the notes you can find is by a researcher who recently killed a zombie alternate version of themselves, and is understandably shaken. In Rebirth, one of the enemies you can encounter in the final loop is a zombie version of your character who can take more damage than a regular zombie.
- Giant Mook: The vaccine is guarded by a Tyrant-like giant monster, apparently called Titan or "evolution monster" by the Rebirth achievements. It's very tough and takes several shotgun blasts to kill, but is relatively slow and can be avoided. Killing it gets you a custom pistol that's more powerful than the standard one. In Rebirth, the creature is instead released from a containment pod when you pick up the vaccine; it's faster than it was in the original game and will chase you through the mansion.
- "Groundhog Day" Loop: No matter how many times you manage to find the vaccine and bring it back to your partner, they'll always manage to get re-infected again. It turns out the two of you (and everyone else in the mansion) is stuck in a repeating loop thanks to the mansion continuously shifting between dimensions. You need to find a way to break the loop to escape for real.
- Machete Mayhem: A machete is one of the new melee weapons in Rebirth. It does more damage than the combat knife and can often kill a zombie with a single chop to the head, but swings a little more slowly and uses more stamina.
- Non-Malicious Monster: In the original game, some of the mansion inhabitants are mid-way into succumbing to insanity, but have not yet become murderously hostile and will just stand around mumbling half-coherently. These do not appear in Rebirth.
- Race Against the Clock: You have 30 minutes before your partner succumbs to the infection. Finishing a loop by bringing him the vaccine will add a few minutes to the clock and restore your health, but you can't reset it entirely and must beat the game before the countdown reaches zero.
- Revolvers Are Just Better: A revolver is one of the weapons in Rebirth: it's quite powerful, but insanely rare. You'll likely not find one in most runs, and it's better to just sell any revolver ammo you find at the recycle machine to make space in your inventory and earn xp for buying pistol bullets.
- Roguelike: The levels are procedurally generated and item and weapon placement is random, so no two runs will be alike. There's also character progression as you can level up your various stats such as aim or stamina, but dying resets you back to square one.
- Time Loop Fatigue: Every time someone shifts dimensions, a few atoms of theirs are displaced incorrectly into an alternate past or future version of themselves. The cumulative effect of this from multiple shifts is what causes the "shredder syndrome" and creates the zombies and other monsters.
