A bit of a stretch, but after you set up a battle you can just watch it unfold without doing anything.

A cool evolution simulator with a lot of detail, you can again just sit back and enjoy cells doing their own thing

You can just create a world, set some parameters, spawn some creatures and watch them evolve.

The game description itself says that players can watch the AI soldiers battle, or take control of one of the soldiers.

A very nice nuclear simulator game. You can let up to 6 AIs play with each other while watching them destroy the world.

Single-player Battlefield with bots. You can start a new game, and just spectate to see the bots fight each other with vehicles and on foot.

The point of the game is to observe a world map where random events happen. Not the best implementation, but good to relax when you're bored.

You can create a custom game and be a spectator in it to watch the AI play. With the sandbox mode you also get the ability to spawn units for different sides.

Still one of the best geopolitical simulation sandboxes out there. There's no observer mode in the game, but you can just choose a small remote country and watch the world evolve by itself.

A decent recreation of Capitalism Lab with more modern looks and unique changes. You can start a new game, sit back, and watch the AI companies compete with each other.