Citadel (2016)

Citadel is an indie cooperative survival game with rogue-like elements. Become a prisoner of the Citadel - you will discover a hardcore gameplay full of pain. Each level is a randomly generated labyrinth filled with unique challenges, enemies and traps, and you only have a short period of time to find the exit. Collect Synergy, which acts both as a health and a valuable resource which is needed for activation of portals and unlocking new abilities. On each level you can meet other random players, who you can discover new places and overcome tough challenges with.