Ecks vs. Sever is a first-person shooter developed for the Game Boy Advance. Players select either Ecks or Sever, each featuring unique missions that intertwine throughout the narrative. The game presents a 3D environment utilizing 2D sprites for enemies and weapons, reminiscent of classic shooters. The gameplay emphasizes action and strategic level navigation as players progress through their respective campaigns.
At the beginning of the game, players choose which character, Ecks or Sever, they wish to control. Both characters' plots intertwine and are given different level designs for each of their missions.
Gameplay is similar to other early FPSs such as Doom in that all of the graphics for enemies and weapons are 2D sprites in a 3D setting.