Google announced earlier this month that indie darling platformer Celeste was making its way to Stadia "soon." The company made good on its word: you'll be able to pick the game up today for $19.99. Google also announced August's free games for Pro subscribers: Metro 2033 Redux, Strange Brigade, Kona, and Just Shapes & Beats.
Tough-as-nails platformer Celeste was a breakout hit in 2018, and prior to arriving on Stadia, was available on every current-generation console plus PC. You can get it here.
Both Metro 2033: Redux and Just Shapes & Beats have been on Stadia for some time, but Kona and Strange Brigade will be new to Stadia on August 1. You'll be able to play all four for free if you're a Pro member. Rock of Ages III will also be a free Stadia Pro game starting August 14. Zombie Army 4: Dead War is leaving Stadia Pro at the end of this month, though, so make sure to claim it if you haven't already.
Google also announced that you'll be able to try Stadia over mobile connections starting today. To enable playing over 4G or 5G, open the Stadia app, tap your avatar, go to Experiments, and flip the toggle next to Use mobile data. (I wouldn't recommend this if you have a data cap, though.)