Doom is a 1993 PC (DOS / Windows) game from id Software, catalogued here for 8 defining game mechanics.
PC (DOS / Windows)1993Complexity 42/1003DPopular
Doom is a 1993 first-person shooter game developed and published by id Software for MS-DOS. It is the first installment in the Doom franchise. The player assumes the role of a space marine, later unofficially referred to as Doomguy, fighting through hordes of undead humans and invading demons. (via Wikipedia)
The genre Doom helped define
First-person shooter. fast 3D combat, deathmatch, and modding set the template the genre followed for years.
The game mechanics of Doom
Boss EncounterCombatA single high-health enemy with unique scripted behavior and distinct phases serves as a gated progress challenge.
Real Time Action CombatCombatCombat resolves continuously in real time; player inputs compete directly with enemy behavior each frame.
Weapon SwitchingCombatPlayer carries multiple discrete weapons with different properties; active weapon is selected from inventory.
Ammo ManagementResourceWeapons have finite ammunition tracked separately from weapon ownership; running dry forces behavioral change.
Flag GatingProgressionA boolean or enum stored in global state determines whether an event, path, or interaction is currently available.
Key LockProgressionA specific named item in inventory unlocks a specific named obstacle in a one-to-one correspondence; item is consumed.
Linear LevelsWorldWorld consists of discrete stages played in a fixed sequence; stages are self-contained with no backtracking between them.
Each mechanic links to how to build it in Godot, with the retro games that share it.
Study the source
Open-source engine (GPL-2.0). Chocolate Doom is a historically accurate source port; id Software released the Doom engine source under the GPL. https://github.com/chocolate-doom/chocolate-doom