Unreal Engine is now FREE. FREE for game development. FREE for Virtual Reality. FREE for education. FREE for architecture. FREE for film. Pay a 5% royalty on games and applications you (commercial) release. The 5% royalty starts after the first $3,000 of revenue per product per quarter. Pay no royalty for film projects, contracting and consulting projects such as architecture, simulation and visualization.
Source 2 the brand new engine from Valve has been announced and it will be free for content developers.
Ascent – The Space Game is an online multiplayer 3D space simulator with Combat, Trading, Exploration, Starbase Construction, Research, Custom-built Ships, Planetary Mining and Farming, Asteroid Mining, Gas Giant Harvesting, Wreck Salvaging and Colonization! You can try a demo of the game, currently in Early Access.
Supernova is Bandai Namco’s MOBA Free to Play. Sci-fi universe that offers upgradeable minions, crafting from drops, the mysterious Supremacy ability and lots of commanders. The Universe is your Arena.