Nuclear Throne - Post-apocalyptic roguelike-like top-down shooter about mutants.
Star Trek Online - Star Trek Online (STO) is a free to play MMORPG that takes place inside the Star Trek world.
Enter the Gungeon - Enter the Gungeon is a gunfight dungeon crawler following a band of misfits seeking to shoot, loot, dodge roll and table-flip their way to personal absolution by reaching the legendary Gungeon’s ultimate treasure: the gun that can kill the past.
EVE Online - Player-created empires, player-driven markets, and endless ways to embark on your personal sci-fi adventure.
Star Conflict - Star Conflict is a free MMO action game and space simulator that was introduced in 2012.
Kerbal Space Program - Build spacecraft, fly them, and try to help the Kerbals to fulfill their ultimate mission of conquering space.