Now this is a very fun and interesting game. Few quarrels with it, so I will get those out of the way.
The guns, I like the guns.. if I knew what their names were. Upgrading one gun thinking it was another was a bit of a pain, then I saw the barely visible (or it just didn't catch my eye till wave 13) text on the bottom when I switched weapons. Which is another thing, had to scroll through all kinds of weapons just to get to the one I wanted, and I couldn't switch guns while reloading. Now these things might have been designed to make the game that much harder, I don't know but it bothered me and actually got me killed at wave 19. Also the background is so bright, made my eyes hurt after a bit, don't know what you can do with that, as it would make the enemies harder to see if you darkened it or easier to see if you made them brighter. Also, I played the first one a while ago... can't tell what is different in this one... Maybe just an updated version or I am mistaken. I think thats about it on the cons. Also I put the game on easy, and I was upgrading the buggun because it is just awesome, but by the time I got to level 19 it was utter crap against the enemies and I couldn't kill anything and then died, course I died trying to switch to another gun and couldn't find a good enough one to take out the hulking masses of monsters. Maybe I was on level 20... yea I was :). Also would have liked a campaign mode or something, course I do know that there is Survival in the title, just a suggestion. Wish there were more interesting ones that did out of the ordinary type of things, but then again I only got to level 20. Also the enemies were pretty interesting bug theme going on... then there were these golem things, and other odd things thrown in, I mean that's pretty cool, it was just inconsistent and caught me off guard a little. Also I wish there was a way to upgrade the base, and give it better weapons or something of the sort, like I said before this said 2.. maybe this is just 2 survival and the other one I was thinking of was the one with the campaign in it... if so disregard all pertaining to the whole "this is a sequal and there is nothing new" spiel :).
The pros :), I loved the Crimson Land type upgrading perks type system. The graphics are pretty awesome, the music and sounds are great, and the interface is smooth and responsive. Instead of going back and erasing the whole sequel stuff, you should make a sequel, adding more things, hell I would download this game on XBLA if there was 4 player coop and all kinds of things even if it was an indie game, in fact that would be better if it were an indie game. I am not joking around here you have something that you can really go with and you can really bring something to the table in terms of game play. Most of the games now a days are quite crappy, or they are good, but don't support coop for some god forsaken reason. Chaps my ass I tell you ;).
ALL in all, this is great, but lets see more content, and not just rehash a great game into a survival mode, I thought this was a new one because of how long it took to come out, or you just forgot it in storage or something lol.
Anyways keep up the awesome work and I am quite excited to see a sequel and think big my friend, you can have all kinds of things going for you if you keep it going and don't let people bring you down, the only reason why I have cons in my reviews, is only to help the author make it better, thus making themselves feel better about the work they are doing/have done.
(I just kept typing, so much I have like 400 characters left lol)