Steam now offers Early Access to WARSHIFT, a space game created by a lone developer that combines action, RTS, and RPG gameplay. Here's a trailer offering a look at how this works, and here's a brief description:

WARSHIFT is an indie experimental project where Action, RTS and RPG gameplay elements are combined in one space epic. You can build bases, manage armies, and then come down to keep the enemies at gunpoint, gain experience in dynamic battles and customize your main characters and vehicles. This project is being developed by just one person - Cyril Megem, who is both artist, game designer and programmer in this project. He worked hard to implement many his and community's innovative ideas in this game.