Another vote for Assetto Corsa. Ultimate is not the lowest price it’s ever been but still worthy of the price IMO considering how many hundreds (cough thousands) of hours I’ve gotten out of it. If you do get AC, I’d highly recommend a few things:

Content Manager: AC is great because of all of the mods it has built up over the years, but everything starts with Ilja’s (x4fab’s) Content Manager (now referring to as CM). This is an alternate (better) launcher and enables the use of the Custom Shaders Patch (included with CM).

Custom Shaders Patch: CSP brings a whole bunch of advanced settings and capabilities for everything from visuals to physics to how your driver reacts as you drive, weather and more. Both CM and CSP have free and paid versions so you can try them and if you like it you can pay a few bucks (literally) and unlock a whole bunch of additional features. I highly recommend both of these at the very least. The previous CM link has instructions on getting a full CM license through Itch.io. Paid CSP can be obtained via the linked Patreon.

Pure: This is an advanced weather controller from Peter Boese that utilizes CSP’s capabilities to bring fantastic dynamic weather, scheduled conditions, and absolutely beautiful skydomes. I also highly recommend this not only because Peter is awesome, but it’s also incredibly cheap. Peter also made an earlier weather controller known as Sol, but that is now outdated and completely outclassed by Pure. Don’t forget, in game rain comes from paid CSP, not Pure! Lots of people mix the two up since this is a weather controller.

Beyond that, you will find tons and tons of free and paid mods for cars, tracks, track skins and extensions, post-processing (PP) filters (to make the game look even better), sounds, etc. If you want it, it probably exists.

Edit: decipher_jeanne brought up a good point. Default controller support is pretty bad and can really ruin the AC experience. Thankfully, with CM and CSP, we have GamepadFX and custom controller scripts! For controller play I highly recommend Akeyroid7’s Advanced Gamepad Assist script.

Maybe they updated since your post but literally all of these things work both in browser and in Steam itself.