FreedroidRPG

FreedroidRPG is a long standing FOSS-project that I have always found impressive. Cool ideas and gameplay, graphics are very well made, and there is a real impressive story in there. An advanced dialog system, the ability to take over enemy robots and lots of other cool gameplay ideas make it feel fesh and different. I have only played it a bit, so I don't know how much content there is. But there have been many substantial updates over the years so there should be quite a lot of role-playing to sink your teeth into. The latest release, 0.16.1, is more a of a fix release. But don't let that deter you, there are lots of stuff to play here, so if you are looking for a really nice single-player RPG this is one to try out!

Very very well made isometric graphics. Overall the game is extremely polished.