NeonXSZ is an interesting fps with six degrees of freedom (6DoF) that pays tribute to classics such as Descent and Forsaken. It is still in development but an alpha version is already available.
“NeonXSZ is our little homage to Descent combined with the frenetic adrenaline pumping feel and gameplay mechanics of Quake. Then add Diablo’s loot explosions, rpg elements, levelling up, procedurally generated environments and enemies. Finish it all off with truly open-world gameplay inside a micro-ecosystem of up to one thouasand unique little AI dudes from four seperate warring factions and the result is a game quite unlike anything that has gone before.”
Game is still in development (Alpha version available)