RimWorld

This is a 2D birds-eye-view tower-defense game with a science-fiction spin. While there is a strategy element, the main focus of the game is storytelling. I played over 600 hours before I'd had enough!

THE GOOD:

• This is an intensely addictive and fun game.
• Play virtually any kind of story you want, so long as it involves a handful of colonists trying to survive on an alien planet! I once tried a primitive start, with my bow-and-arrow wielding people living among dinosaurs. They survived, thrived, and eventually had omni-bots doing all their work for them. It was epic!
• The game design is really great, where the controls allow you to do everything you want, but it's designed so it's easy to lose track of some details or forget something. There's plenty of opportunity for excitement and drama, whether it's created by the game's built-in storyteller (who throws events at you), from your own mistakes, your colonists' interactions, or just your imagination.
• The game is backed by some really fun and thoughtful science-fiction.
• The mod community is amazing and gives the game tons of staying power and replayability. Every player has their own list of must-have mods. Mod management through the Steam Workshop is pretty simple.
• There is an incredible multiplayer mod available that smoothly enables co-op play.
• I played through the Royalty expansion and it also adds a lot of really fun extra gameplay, as well as a cool new win condition, and is worth picking up.

THE BAD:

• After some hundred of hours of gameplay I started to see the pattern in the main storyteller (Cassandra)'s semi-random events. This was solved by switching to everyone's favourite storyteller: Randy Random.

THE UGLY:

• In 600+ hours of playing this game (some of it offline, so Steam didn't count it), I've had the game crash on me once or twice. Otherwise, it's really stable, even with lots of mods running.
• The developer once updated the game in the middle of my playthrough via Steam, and there was no way to stop this. This broke the mods I was currently using and ruined a game in progress. I was able to find a workaround, but it was difficult. This issue has since been fixed, with the developer allowing you to pick an earlier version of the game if you want.