During research on the accessibility of games I discovered that some guidelines are very easy to apply. I want to explain a few of them. I hope it will help you to get through some of the guidelines for accessible games.
Color and other design
Mind that there are a lot of gamers with a visual disability. These people struggle with some fonts with serif, so use a font without serif. It should be easy readable. Also these people struggle with the contrast of the colors on the front and in the background. There are a lot of ways to pick these colors.
I prefer using this tool: http://www.dasplankton.de/ContrastA/ It shows that if two colors are accessible together and you can also see how colorblind people see the colors. Google Chrome has a tool like this and there is a lot of free software. So picking your colors is not a difficult job!
Most of the people with an auditory impairment are still able to play games. But sound gives feedback to the player, often in addition to visual feedback. As a game-developer, make sure all the essential information in a game is not only conveyed by audio alone. For people with a visual impairment the audio is much more important. In the game itself, audio feedback helps the player feel his actions have an effect. An example is the sound played when a gun is reloaded. Blind people play audio-games: games that are playable with only audio. Take a look at the Curb Game. The audio forms part of an award system. Think of completing a row in Tetris. It’s an achievement, so a game-developer should also make it sound like one.
Keep in mind that all people need to understand the instruction if they want to play your game. Use simple clear text preferably in combination with visuals. Essential information can be reinforced with visuals. Make it possible to read the instruction again and let the gamer decide when he wants to close the instruction. It can be very frustrating when you’re reading the instruction of a game and it flashes away (too fast). Although text is mostly needed, avoid too much text.
Gamers of all levels want to play games. Therefore include an option to adjust the game speed. Make sure there is a wide choice of difficulty levels. Some people may also like a level to practice without failure, such as a sandbox mode.