With the question for smaller solo games already posted I want to ask if any of you got some large and deep solo games. I'm usually someone who does enjoy longer, bigger and deeper games (not saying small games can't be deep). But when things get more involved and complex, that's where I feel at home.
Even though I do usually not enjoy solo play, I can recommend Spirit Island. As different spirits you take on settlers corrupting your Island. Besides every spirit having a completely different play style, it can be as challenging as you like, as you have multiple options to give the settlers different strength levels with unique strategies. It is a coop Multiplayer boardgame which works really well while playing alone.