I'm going to preface the following with the fact that I'm not an accessibility expert and accessibility is not a field I'm interested in. With out more info on the software it's impossible to give specific suggestions. For a tool that produces structured diagrams such as flow charts a way to move from node to node with arrow keys and have announcements on what connects to what would be a good way for me to read flow charts with out being able to look at them with my eyes. If your creating a color matching game for two year olds I can't think of any reasonable way to make it accessible. Other people may argue the game should announce colors and have a mode to pick them based on words only but at that point your starting to write a completely separate game.