Great overall, but could use some minor tweaks.
Great graphics and overall game play. The different modes really showcase the different aspects of the game, and I liked the feel of combat mode and the focus on skill and timing to help an overall push. To further emphasize that, I think you had just the right number of weapons and abilities: enough to have options, but not so much that you're swamped deciding what to use. There's definitely been a lot of effort and hard work put into this, and it's obvious; the decent voice-acting and stats screen are also appreciated.
On that note, I have to say that there were numerous flaws each on a small scale that kind of took away from the enjoyment of the game. The story was a bit short, so it leaves the game a bit lacking, especially since the only other mode you have is Survival, which after a few waves becomes pretty monotonous. Maybe I just didn't try enough keys, but for cut scenes and dialogue a skip for individual lines would be nice since it wouldn't continue until the subtitles finished - which tended be long after the actual character stopped speaking.
For variety, I'd consider some other modes such as Custom or even 'Challenge' missions of some sort. Suggestions for survival and any similar modes to follow in the sequel: a kill count and an elapsed time. I could be the only one who likes having that visible though, so perhaps make it an option you can turn on? While I thought it was just right, it's always nice to have choices so consider implementing a difficulty setting as well.
Again, I thought the game was great overall, just look at ways that you can expand upon what you already have going for you while working on the little things. 7/10. I need room to give a higher score for the sequel, right?