Unlike rifles the RPG launchers may cost more than the rifles and do less base damage than the rifles. It's because RPG will explode upon impact, doing damage in a radius. Killing monsters refuels your abilities and provides you with income to purchase stronger weapons. Enemies randomly drop blue upgrade tokens that go towards leveling up your currently equipped weapons. When you're selecting a weapon to upgrade, consider that the more you use it, the stronger it will get. It's important that you keep moving in Xenowerk or you'll be dead in seconds. Keep in mind only a few enemies have ranged attacks in the game.