Thanks for the support :)
I also had one of these old electronic handhelds as a kid (mine was Scramble), with super bright neon-ish colors. The heavy use of bright cyan is a tribute to this look.
As for sound effects, I am currently trying to get to know the SID a little better. I would very much like to add the option of sound effects, but first I have to make some that sounds really cool :) I might need someone to help me with that though, as I am not an experienced synth guy.