Regicide is my final pick for this list. If you love WH40K, and you also love chess, then this game is your bag. For me, it takes me back to the 80s when I spent countless hours sneak-playing Archon: The Light and the Dark on school computers. Except these chess matches take place in the grimdark of WH40K, which means some exceptionally brutal combat.
Regicide is of course available on Steam.