Thanks for checking the game out! I'm glad it's up your alley.
That exact accessibility concern you described is on my list of future updates (it's listed in the game doc itself) and should be coming sooner than later in the process. The plan right now is to go with the color and pattern combo similar to what you described here.
I'm also looking into ways to do alt text descriptions of the patterns and such for folks too (but that one is likely a bit further down the road).