Pretty Good...
This game was pretty good, but got pretty boring after getting all the weapons, and it was pretty easy after finding a flawless strategy. Like saving up for a shotgun and then saving for a Famas. That's when you'll never die, pretty much the begining of the end for this game since after this, you'll have all the weapons in the game in no time.
This is a very great game even if it is really easy, but this game could've gone so much farther, like maybe some CPUs in the game just for kicks, or saving some random NPC, or whatever floats your boat.
The mistake that people usually make is that the Pancor Jackhammer is the best weapon. It's not. The best weapons to use in the early stages of the game are as follows: (just including this for those who want to get better at the game) The first handgun, for about the first three stages, then the Mossberg 500, then a Famas. After that, just save for the character upgrades, and the occasional re-healing of your base and yourself, and of course, upgradeing your and your bases health. Then just nab yourself a Five Seven and you're good to go from there.
By the way, I've checked the highscores, and it seems that people MAY have hacked the game. 1e+6 was one of the scores I saw up there, so, that lead to suspicion, that is of course, unless there's a glitch where the game just changes the score to numbers and symbols after reaching max.
Hope I was of help.