While the name is a clear riff on Dead Space and Mass Effect, the actual gameplay is heavily reminiscent of Doom³, with players travelling through the corridors of an abandoned spaceship while battling hordes of zombies comprised of the ship's transformed crew. The sequel had also added Borderlands 2-style RPG Elements to the series' formula.
Players take the role of either Space Marine Gunnar Davis, or cybernetically-enhanced Dark Action Girl assassin Jane Frey, as they wake up from hypersleep on the starship ESS Meridian to find the rest of their Space Marine squad missing and the crew of the ship transformed into flesh-hungry zombies. Guided over the intercom by a surviving scientist named Dr. Wagner, the player must navigate the ship and find a cure before they also succumb to the zombie virus.
Dead Effect features examples of the following tropes:
- Ambiguous Situation: Wagner claims you're just a test subject in a military experiment to create a supersoldier, but not only is he out of his mind, this contradicts a lot of the logs you find lying around. Unless they were planted to help conceal the truth about the experiment and convince you that you really are just stuck on a colony ship during a zombie outbreak- but if that's the case, why do so many of them foreshadow that Wagner is responsible for the zombie army? The sequel indicates the Meridian really was a colony ship, most of the zombies you encounter are clones created by Wagner (most of the actual crew is still in cryosleep), and Wagner took over the ship and converted it into a testing facility.
- Badass Normal: Gunnar's an unaugmented human Space Marine, whereas Jane has a number of cybernetic enhancements. In-game the two play identically. Though it turns out the player character was a test subject for experimental human augmentation treatment prior to the events of the game, which is why they're in the situation in the first place.
- BFG: The explosive crossbow is this. Even without upgrades, it one-shots any of the Elite Zombie types (including the Boss in Mook Clothing Giant Mook with a minigun) and knocks off about 80% of the first boss's life bar and over 1/3rd of the Final Boss's life bar with one shot. It even uses normal primary weapon ammo, so you can use it pretty liberally without worrying about running out of ammo. The only downside is that it uses up your primary weapon slot, so you'll be limited to it and a sidearm, which leaves you without an automatic weapon to deal with the fast-moving "demon" enemy types (cannibals).
- Boom, Headshot!: As in most zombie media, headshots are the most ammo-efficient manner of dispatching the zombies, though zombies can still be killed with several torso shots too.
- Bribing Your Way to Victory: The mobile version of the game incorporates micro-transactions to buy weapons and weapon upgrades, although these upgrades can be earned in-game as well, and the amount of grinding required to do so is not obscene. The PC version is in-game currency only.
- Bullet Time: After the first few levels, you gain the ability to trigger slow-motion bullet time as a special ability. It's explained as a side-effect of the virus that will eventually turn you into a zombie.
- Chainsaw Good: As well as the tough fat zombie wielding a chainsaw, the player can unlock one to use themselves. It takes the secondary slot (despite that being designated for "one-handed weapons", while the chainsaw is clearly big enough to require two hands), never runs out of ammo and rips through zombies like cardboard boxes, but you still need to aim it carefully to keep them from lunging under it to hit you.
- Cyborg: The only organ that Jane doesn't have implants in are her boobs.
- The unique minigun-wielding zombie, codenamed "Hornet v.1", is a combination of zombie (a Razor clone) with cybernetic enhancement.
- Difficulty by Region: The PC port has a lot more zombies attacking you at once, to compensate for the increased responsiveness of the keyboard & mouse setup compared to playing the game on a tablet.
- Which in turn leads to better game rewards, as Microtransactions are removed in the PC version in favor of one-time purchase.
- Elite Zombie:
- Hazmat zombies have more health while Security Guard zombies wear body armor, which allow them to survive noticeably more damage than other zombie types.
- The game has 4 "special infected"-type zombies. There's an armored zombie that throws one-hit-kill grenades, a tough, fat zombie that spits acidic blood, a very tough fat zombie armed with a chainsaw, and a Boss in Mook Clothing armored Giant Mook armed with a minigun. Additionally, there's also a boss zombie that's larger and has more health than any other zombie, and the final boss.
- Emergency Weapon: The taser glove you start the game with. Although it doesn't use ammo and pops regular zombies with one shot, it's limited to very close range and has a recharge time of several seconds between shots.
- Gatling Good: One of the game's weapons is a minigun (it's one of the three weapons that can only be purchased with gold rather than credits). It deals less damage than the higher-end assault rifles, but has a high rate of fire and can be fired for a very long time before needing to reload.
- Giant Mook: One of the Elite Zombie enemies is a heavily armored soldier wielding a minigun. He moves slowly and takes a second or so to spin up his weapon, but can mow you down quite quickly. He can also survive a lot of damage before dying. And, stating the obvious, he's a zombie with a gun!
- Gone Horribly Right: The titular Dead Effect allows people to be killed and resurrected as stronger, faster, and hardier versions of themselves. Predictably, it shits the bed and creates a Zombie Apocalypse.
- Heavily Armored Mook: The aforementioned minigun zombie.
- Grenadier zombies wear riot armor and chuck grenades.
- There are also zombie Space Marines whose combat armor makes them very hard to take down with body shots.
- Herr Doktor: Dr. Wagner has an extravagant German accent and is a fairly stereotypical mad scientist. He turns out to be the bad guy. Who knew?
- Irony: The observation is made in-game that Jane Frey's boobs are the only part of her body she hasn't had artifically augmented.
- Kinetic Weapons Are Just Better: There is precisely one energy weapon. The rest are kinetic.
- Lightning Gun: The Electromagnetic Stun Gun, affectionately called the "Tazer Gauntlet" by fans.
- Limited Loadout: You can only carry a limited number of weapons at one time (one pistol, one longarm, and one grenade), and are only able to switch weapons on the level loading screen.
- Multi-Mook Melee: Besides the single-player campaign, there are two different types of "Horde Mode" arcade game modes where you battle waves of enemies inside an arena-like area- Survival, where you survive against infinite enemies until time runs out, and Biohazard, where you fight your way through a fixed number of waves of predetermined enemies.
- Muscles Are Meaningless: The log file that details Jane Frey's background mentions that she's been heavily augmented, and jokes that despite her relatively slim figure she could probably fold Space Marine Gunnar Davis in half. In-game, though, there is no difference between the two player characters.
- My Brain Is Big: The first time you see Dr. Wagner in person you discover his brain is bulging out of the back of his skull, which seems to have been removed to make room for it.
- My Death Is Only The Beginning: Dr. Wagner mentions in a collectible log that he's programmed the ship's A.I. to manage the D-Effect experiments (including control of automated cloning facilities for the production of more zombies), and that it will continue his work if he ends up dying fighting the player.
- New Game Plus: You can revisit previous levels with whatever new weapons, weapon upgrades, and character upgrades you've purchased. There's also a "New Game Plus" mode that has you play through the game again with significantly increased difficulty.
- Not Using the "Z" Word: Averted. The first word the player character yells out is "Zombies?!" as soon as Dr. Wagner explains the creatures are members of the ship's crew who have been killed and revived by a virus. Wagner deadpans "You can call them that."
- 100% Completion: Each level has a number of cash, text logs, and hidden orbs to find in order to achieve this.
- One-Man Army: Per First-Person Shooter standards, the player character mows their way through hundreds of enemies over the course of the game. This turns out to be justified in-game; the player is a test subject in experimental military Super-Soldier research, with the whole game being a fabricated scenario designed to test their abilities. Or at least that's what the Big Bad claims, but he's nuts.
- Only Six Faces: The zombies only have about 10 models. Justified as the Big Bad cloned the ship's crew several times, resulting in a zombie horde that has shades of Me's a Crowd.
- Our Zombies Are Different: It's hinted at in the collectible logs and more or less confirmed in the sequel that most if not all of the zombies are actually cloned test subjects rather than turned crew members.
- Regenerating Health: The game does not have this by default (you have to heal at health stations), but it can be purchased as a special ability (although the currency you need to buy it, gold, is a rare drop, so it will require quite a lot of gameplay before you can afford it).
- The Reveal: Turns out Dr. Wagner is evil, and deliberately mutated the crew and converted the ship into a combat testing ground for his experiments, which also involved mutating you and gauging the results as you rampaged through his hordes of zombies. Dr. Wagner claims the ship is actually a military testing facility, but the collectible audio logs reveal that he's delusional and that it really was a colony ship, which he took over. Oh, and your character may or may not be a clone of the original Gunnar Davis or Jane Frey.
- Removing the Head or Destroying the Brain: The zombies can be killed by body shots, but a headshot with any weapon is an instant kill.
- Revolvers Are Just Better: Averted in the Early Access alpha version. The revolver dealt more damage than the semi-auto pistol, but it only holds 6 shots and the reload speed was extremely slow. Since most zombies can be killed with 1 headshot regardless of how powerful the gun is, the more nimble semi-auto pistol was simply better for everything. The reload speed and damage of the revolver were boosted in the actual release version of the game to make it more competitive with the semi-auto pistol, and it's now a typical FPS revolver (high damage in exchange for being limited to only 6 shots before reloading, although the reload speed is now reasonable.)
- Schrödinger's Player Character: Although both Gunnar and Jane are mentioned in the log files scattered throughout the ship, only the one you pick actually shows up in the game, with the other one completely absent. Possibly justified in that your character may be a clone created for combat testing purposes; the real Davis and Frey may have already been woken up and failed to stop Wagner previously.
- Separate, but Identical: In the original mobile version of the game, there's no real difference between Gunnar and Jane. In the PC port, Gunnar's default equipment is a semi-automatic pistol and an assault rifle, while Jane's default equipment is a revolver and a shotgun. Jane's weapons do more damage, but hold less ammo and are very slow to reload, making her a noticeably more challenging character to play as (although you can spend in-game credits to purchase other weapons).
- Sprint Meter: A particularly jarring example, as these two highly-trained and cybernetically-enhanced super-soldiers literally can't run for 5 seconds at a time without running out of breath and being forced to wait for a good 15 seconds to get it back again.
- Standard FPS Guns: With the unique feature being that the "Knife" type weapon (The Electromagnetic Stungun) deals a One-Hit Kill with Splash Damage.
- Title Drop: Dead Effect refers to the augmentation treatment that was intended to make the crew more efficient in space, but which ended up turning them into zombies.
- Treacherous Quest Giver: Turns out Dr. Wagner, who's been your guide for most of the game, is actually the Big Bad.
- Tyke Bomb: Jane Frey's backstory explains that she was adopted by the military and raised from childhood to be a weapon.
- Unique Enemy: The minigun-wielding zombie only appears once in the single-player campaign, even though it doesn't have a boss meter and is more of an Elite Zombie. In contrast, the actual boss zombie (Captain Razor) appears at least twice in the campaign, thanks to him having been cloned by Dr. Wagner.
- A Winner Is You: After you kill the final boss, a short cutscene plays of him exploding, a congratulations message from the dev team pops up, then the game immediately cuts to the credits.
- Zombie Puke Attack: The fat zombies in jean shirts gob acid blood at you. When they don't have chainsaws that is...
