Just wrapped up Contra with using the default weapon. Had to use a continue and two more lives to do it though. It wasn't as bad as I thought it would be as you can run through a lot of places without having to kill stuff. The hardest part of the shooting was the tanks/cars with spikes in the snow stage (level5?). You could barely finish them off before they run you over. Everything else took a bit longer but you could dodge and repeat the pattern.
I tired Contra Force and I guess I don't remember that game. It had terrible lag and I couldn't make it past the first level without dying due to lag. It was nowhere near as smooth and enjoyable as the first two so I gave up after about 15 minutes.