Double click the green flag. Just guess until you get a message that says "you got it correct !" Pretty basic but its possible.
A game written in JACC 1.2? Yes it can be possible with the addition of sprites (Even though I didn't use it in this particular game). The making of Guesser: A game like this was possible from JACC 0.2 when random variable and if<> block were added. All I did was just took advantage of all the new features since then and then i used the JACC 1.1 to JACC 1.2 converter to convert my code.