The somewhat new Deep Rock Galactic: Survivors. Its a singleplayer 2D horde autoshooter version of the game, with the same design / voice acting as the main game but randomized runs where you find different upgrades and weapons leading to lots of cool valid builds to go for.
Its in Early Access rn but if they devs put 10% of the love they have for the main game into it, then it will only become greater. Its 9€ rn and the devs already released a roadmap with great future plans.