OpenClonk

OpenClonk is a very unique title, combining realtime strategy with platforming. Described as a "multiplayer-action-tactics-skill game", you have to mine for resources, construct buildings and fight other players or computer opponents.
OpenClonk just reached version 4.0, including some very interesting new scenarios among loads of other improvements.

Clonk takes a while to learn, and it's one of those games I'd like to play more so I really can get into it's unique gameplay.
Filled with content and with lots of attention to detail in it's presentation, OpenClonk is a very cool project. If you feel like giving it a try, get it here!