I think one of your jobs as a game designer is to make a lot of hard choices, so the the player doesn't have to, and can focus on having fun.
Also, implementing both, is double the work, and the gain not that clear.

Unfortunately (for those players) very few players enjoy fiddling with endless options.
I've actually tried to play dwarf fortress, and its a pretty horrible experience.

The problem isn't really that its complex and has a lot of choices.
The problem is that you get absolutely no help from the game in navigating those choices.

Dwarf fortress could be a great game and reach a big audience if they cleaned up the experience.

Don't confuse "easy to understand" with "simple".

It doesn't have to be reduced to the one "win" button, a game can both have a depth, and be easy to understand.

I definitely see Menyo's point, and personally I love games with more depth and complexity to their mechanics if they're well balanced and I have the time to get in to them -- but I would suggest that gamers such as myself and Menyo simply aren't the casual target market specified in the OP.

I agree , and i don't know the stats of each weapon so can't really comment on that. But let's say for each gun you can increase it's speed or power, or decrease it's energy cost. These are pretty simplistic options that can be clicked through fast enough once a player reads a short description. But then again, the game isn't aimed for me and i always had a hard time understanding why people play casual games .

Thanks everyone for all your responses, I read most of them as they came but didn't have time to properly respond to them.

I decided to do what most of you said, and that is to keep it simple with a single upgrade button for each weapon. So they basically have to decide which enemies will die faster in the next round (So any enemy they kind of had trouble with they could upgrade for the next round).

Also jbadams, I like your interest idea and implemented it, it works well and is a good risk VS reward but needs a bit of tweaking!

I did like your idea ImmoralAtheist but the extra amount of art assets and code required would probably break our deadline.

And for what you said just above Olof I completely agree, pretty much everyone I have worked with are astounded at the fact that people don't intuitively know how to play their game, they then blame the users even though it's not the users fault.

Thanks again!