I recently put more thought into Nexus-Defense, and I have decided not to make it level based since my original idea was to make the first 10 levels of the game, where you would have to kill X amount of mobs to progress though the game until you get to the last level.
For the time being, I've decided to make the game one level only, but I will add things in it so it'll be fun and enjoyable to play. Such as a level system, kinda like in World Of Warcraft where you will have to get X amount of experience points in order to level to the next level. I also made a pause button which will be released in the next updates, so you are able to pause the game for X amount of minutes. I have a few more ideas in thought, and I will share them with everyone who is following my game development progression.
I also made a twitter account early tonight. I will be posting quite a lot of updates on my twitter page as I progress with my game and future ideas. If you are interested in following my progression, then please follow me on twitter at https://twitter.com/Ghostcrawler336
I'm also open to any type of feedback or suggestments you may have to make Nexus-Defense a better game.