I've owned several of the galaxian multi games.
I really like them, mostly because I was seriously into shooting games as a kid. So I have great memories playing all those crazy games.
My galaxian multi's came from the same guy.
There was a 24 in 1 and later a 12 in 1 and 8 in 1.
Someone also told me that there would soon be a Scramble multiboard that plays tons of those galaxian style games. I guess its basically the same set-up.