THIS!
Weren't we just talking about colorforms yesterday? I used to love playing with this set, and can't say I hated the experience messing around with it today. It was the only non-girl toy I really had all my own. I had the token Barbies, tea sets and a couple Care Bears, but The Brother (as I sort of fondly call him behind his back) had ALL the toys I wanted- Teenage Mutant Ninja Turtles, Transformers, GI Joe stuff from the cartoon. He was constantly complaining that I was taking them or he was breaking them... cause he was a boy and they like to eviscerate their stuff, which is why I stole his toys cause he didn't appreciate them. For some reason though I got the Ghostbusters colorform!
Luckily, I was a pretty fastidious kid, so as far as I know everything's still in the set. I do have a feeling however there's supposed to be a couple more slime green footprints....
(Egons proton pack seems to have misfired...)
(this guy was always my favorite)