The Prizm hacking community is rather small at the moment because the calculator is still "new." As for the number of threads, there are several reasons for that. One is that only about half of the Prizm coders are actually on Omnimaga. Another reason is that what's going on is mostly background work to document the Prizm, which doesn't make very good thread material.
Also, games are perfectly possible on the Prizm, but they haven't been made largely because there are too few coders to do everything, so the people who do program the Prizm spend their time documenting it or writing utilities so that others can program it more easily. Games will happen in time, but they're not the priority for most coders at the moment.
EDIT: Also, if you want to come on IRC (you can't access the site's native IRC client until you have 40+ posts), try something like Mibbit
. Just go to EFNET in the dropdown menu, enter a username in the name box, "#omnimaga" or "#prizm" in the channel box and join