awsome
what you have here is an awsome game. and no doubt
except theres a couple of ideas i would like to put forward
first off, the end boss was good, but easy enough for me to ignore him and take down the little guys for a minute. i think if you made the boss take a pre-destined route around the arena so he will always get to you eventually then it would be harder, also i used a emp gun on him and it worked a treat, im thinking that if you make him nearly invulnerable to emp then the player will have a far more challenging boss fight.
i dont know what you think about this but maybe mini boss fights here and there to make things a litle more lively, maybe they have a unique weapon for you to get after killing them, or maybe just killing them unlocks some more weapons to buy.
also im thinking that you might be able to buy different juggernaughts from a button underneath the picture of a juggernaut in the buy menu, you could have
a fast-low health-but extra shield-extra damage one...
a slow -high health -extra weapon slots one...
a medium speed-medium health-and medium everything...
another one with extra gear slots etc
after all that i was a little disapointed that i couldn't (or couldn't find) a way to repeat levels, so an option for that would be good.
maybe you you have a think where you create custom levels for yourself - you could place your own traps, customise which enemies and how many, what weapons the juggs have etc the play it with your campaign juggernaut. maybe you would have to beat cetian levels or mini-bosses to be able to use certain traps/enemies.
basically the potential to have a freakin awsome game here is under your nails, u just gotta pick it out ;)
woop! writing!!! enjoy reading that ^^