War games are fun and all,but if you want a realistic challange without having to worry about prison time,I'd get together with a couple of friends and have a true open hack on each others boxes with the security features you would normally have in place(ie. firewalls,AV's,spyware revoval tools,real passwords,and all that good stuff)Putting a login screen in front of your face and saying get past this can give you some limited skills,but it limits creativity,because in all actuality there's many more ways than that to compromise a system.I would highly recommend making sure you have all of the backups and CD's needed to get your box back into working order and seperated from your computer before attempting anything along those lines.

The fun part about this is that the game adjusts itself to your skill level.If you exploit a hole in a friends system than they(...at least if they have half a brain)patch that hole so you can't go that route again,so you have to use your brain a little more than most war games make you.

Not to say there's not war games out there that don't require a pretty large amount of skill,but beating a war game level that is constant and set for a specific task to by-pass it is no substitute for a real life open hack/counter hack chess match.