That's a lot of probably great games I've missed, so I'll go with Vietcong instead. I really wish it was available somewhere, because I'd like to finish it one day. I originally pirated it a really long time ago and lost my interest at some stage where there were a lot of tunnels, I think - a part I didn't really enjoy much. But until then, the game was great.

Kingdom Come seems like it was going to be a pretty fun game, but something came out and pulled me away from it. Factorio from the demo was a ton of fun. Wonder if it will get mouse support.

This is very tough choice for me, with so much great games.
But ultimately I have to go Machinarium, one of the best P&C adventure games in last 20 years, with fantastic art style and world building.
Honorable mentions go to Vietcong, fantastic tactical first-person shooter from 2003.

Other: Top Spin 4. I really enjoyed 3 & 4 and was happy that studio got to make another one recently.