Welcome
I have some chess assets offer for you, in both Unity and Unreal Engine, please have a look.
Unity Asset Store Assets
The Coolest Chess
A perfect chess template to begin with, having all the chess game logic necessary to play an international tournament standard game, easy to use puzzle tool, and tool that can visualize PGN text file. Two types of build in AI and an option to import Stockfish AI without effort which integrate into the asset seemlessly.
v3.1 will be available on the end of November which focus on improving flexibility and speed of which puzzle level can be created.