Ok with a bunch of help from LRP I have an entry that works in 139 characters! I'm so happy I managed this. I didn't think I'd actually be able to compress it this small. It was a lot of fun to do.
k=2^13::s::for a=0,k do n=0 for x=0,8 do n+=peek(k*3+a+x/3+x%3*64-65) end poke(a,n==12 and 4 or n==16 and peek(a))end memcpy(k*3,0,k)goto s
Was trying to make Conway's Game of Life into a #tweetjam entry but wasn't able to get it below 175 characters. It reads the screen to do the simulation so while it will always display the same simulation from the BBS you can do whatever input data you want if you download the cart by having whatever you like on screen when you hit run.
If anyone can spot a way to compress it more please share!
I entered a game jam a couple of weeks ago with the theme of "punch nazis". This is the result of my efforts - Super Fash Bash runner up for the "Best Nazi Punch" award for the jam.