Procedural space sim with land-able, real-sized planets, with detail down to meters.
Sort of like Infinity the quest for earth, but, single player,free, and on Linux.
Game-play is similar to Frontier elite in scope and openendness (what’s a better right spelt word for that?) but not a clone.
This looks to be one of the few games that are of high graphical quality on open-source/Linux (high at least in the space sim genre).
Coded in C++, game-play scripts (and procedural models) in lua, and open-source.
Code was released a little while ago and devs who have been waiting to work on such a sim are joining as the news spreads, it seems.
Source is on github, and they have an IRC channel on freenode #pioneer.
Long list of features here: http://alternativeto.net/software/pioneer—space-sim/about
On pc and mac too.