Pac Man For Excel
If you have a limited list of applications that your IT guys will let you can run at the office, and MS Excel is on that list, you can still play games at the office now that somebody has created Pac-Man for Excel. It's actually fairly smooth on my PC, but I've heard it'll run a bit slow on older PCs. Also make sure you have Macros enabled in Excel, otherwise the thing doesn't run. But this is by far the most impressive use for Excel I've ever seen.
I've put a mirror copy here in case the guy goes over his bandwidth quota.