Doom is a 1993 computer game developed by id Software, and one of the most seminal titles in the first-person shooter genre. Combining immersive 3D graphics with graphic violence, it became both controversial and immensely popular (Wikipedia).
C2Doom is a Doom port for Nokia S60 and S80 phones. The C2Doom is based on SDL Doom by Sam Lantiga and a version developed from Doom for Nokia 9210, also called CDoom. SDL, Simple DirectMedia Layer is a cross-platform multimedia library that is also ported to S60 and S80 platforms.
The C2Doom for Nokia S60 and Nokia S80 phones offers same game playing elements as the original PC Doom. There are same episodes, maps, graphics and music than in PC version. As orginal version of Doom, also this version has has a multiplayer game - however this time implemented to be played over bluetooth. The Doom games has two separate elements: a game engine and a game data. The C2Doom is the engine and you need game data prior to play Doom.
The Doom game data, episodes, maps, graphics, music, SFXs and such are stored in the the WAD files, which are still property of Id Software. This Doom engine supports many different WAD files, very same files that you have with your PC version of Doom. The most accessible WAD is a shareware Doom 1 episode 1, that you may found from Id Software site.
WAD files should be places in a wads directory on the memory card, i.e. e:\wads\doom1.wad
The newest release of C2Doom now also supports S60 5th Edition phones, including the 5800 and the N97. Touch moves, including running and strafe. Quick tap shoots. Then there are moveable virtual keys that provides rest of the essential keys: Weapon selection, action, enter, map and menu.