Baldur's Gate 3

The C in CRPG stands for "computer", and was originally meant to differentiate them from pencil and paper RPGs, like D&D. That is to say they try to mimic what it is like to play D&D style games, with the openness and freedom that entails.

Obviously that is impossible, since in D&D you can do anything you can imagine and describe, provided it fits in the rule framework and the DM plays along. Including, if the DM is willing, just running away from the story to do something else entirely. But CRPGs usually try to let you have multiple ways to solve the problem of the moment.

There's also a big emphasis on story, and very often quests will be delivered narratively. As in, if you wander into a town you might talk to someone who mentions they have a problem and then it's just kind of… up to you to decide how to help? If you'll help? You don't tend to get a marker on your map and a note in your journal to go kill 5 rats, for example.

Also combat is often turn based and you usually control a whole party. So in short it's not like Diablo really.

It does run on steam deck. I had to switch to proton experimental, and the graphics have to be toned down a good bit for 40FPS stable, but because combat is turn based, it won't get you killed. It also handles reasonably well with a controller. It has enough complexity that some stuff takes more than one level of menu to do, and I've made some mistakes due to the differences with their control scheme for Divinity Original Sin 2, but once you get comfortable with it I think it works pretty well.

I wouldn't even compare it to Diablo.

Diablo is like a fun action packed shooter. Like watching John Wick. You're there for the adrenaline.

BG3 is a deep story game with a LOT of choices, a lot of them can go into weird directions. Like watching Lord of the Rings. You're there to seethe a Elf throws the Dwarf.