laser cannon = "make it go away, mommy!" button :P
i played this yesterday and lost horribly. it was probably cause i invested in the first shotgun before i could do much else.
anyway, i liked the game alot. it was challenging to start, but once i did a bit of research i found a good winning strategy. i saved up points until i could buy the first assault rifle. then i used that and saved up points until i could get overkill, repairing as necessary. once i got overkill, i bought the second assault rifle and saved for bloodlust. after getting that, it was easy to get the dsert eagle, and from there, things skyrocketed. after buying all the weapons and then upgrading myself and my base to 3k hp each, i basically just let everybody crowd around me and the base before scooting off to the side and blasting them all with the laser. instant 3k xp.
btw, you dont have enough room for the xp counter to go over 100k xp. just an fyi ;)
other than that, though, it was pretty fun. i got to the point where everything was easy around 8 or 9 am the second day. id suggest some kind of daily boss that you could fight around noon each day. maybe a giant monster with like 8 or 900 hp or something. just to make it interesting.