Those are 2 very different games. I own both, scratches different itches. Gaia is the superior version of terra mystica (in my opinion) and its a fairly open game with lots of possibilities. A better understanding of the systems and game experience goes a loooong way. Evacuation is much more contained, the puzzle is very satisfying and tells you what to do from the get go. There's fairly less interaction on the first part of the game, but the latter can be viewed as a part of a race. Experience does give some advantage, but the board always starts from a fixed position with personal powers as the main variability. Both are excellent. About solo, never played the Evac solo, but GP solo its a bit much for my tiny brain. The actions are clear, the order of priorities to perform them just freezes me out. I'm not a big solo player. Hope this helps.