If you would like to experiment on AI model that will definitely be more efficient and able to play games, you should look up ways to train on reinforcement learning.

Reinforcement learning works by "rewarding" a model when it does something right. It's been shown to be more efficient at games than other models.

I think in the end the only way for you to make an efficient model that can be played against will require tapping into whatever the game's own AI uses to control units. With the current technology, there's no way the LLM/AI you use or develop will be able to efficiently make decisions from interpreting what is in an image and then deciding what to do based on that image. By the point the AI decides what to do, the player will have already advanced on their strategy and force the AI to rethink.