How to get the PID of a running game which you are not sure about the name of its process?

So I run a game from steam called tomb raider.

I want to find the process.

I need the PID of the game to set it (using taskset) to use 2 specific cores of my system.

The problem is that for example when running htop I get 4 processes that have the name "tomb raider" in them and two of them end in gallium so I suspect on of them should be the right one...

All 4 processes have different PID obviously so how to tell which one I need?