Base Defense is a single/cooperative modification based on horde-style and RPG systems. It's awesome, you should try it ;)
Weapon upgrades system is being replaced with a new weapon tier system. Old weapon upgrading system was weak and not effective, new system is made to solve those issues. As you can see there are 6 Tiers from basic (E) to superior (S) and damage values below. As you upgrade weapon tier its ammo price will be doubled. Now it will be up to your choice what weapon you want to be powerful and what to use when you want to finish the enemy. The more powerful weapon is the more expensive it becomes to use it, so don't miss the enemy and shoot wisely.
n i c e
ohh.. Updates! Nice to see you're working a bit more on this!
Thanks! I'm glad to be back :)