I originally found out about this game from the pick-o-the-week feature at www.macosxhints.com and decided to give it a try since I vaguely remembered the Chopper game of the olden days. Plus it is free, which makes it a lot easier to download. :)
To sum it up, this is a really fun and addictive game and a fantastic remake!
If you haven't played or don't remember the old Chopper game, the object is to pilot a helicopter through a level filled with enemies to rescue civilians which are scattered throughout the city. The enemies consist of bazooka men, tanks, jets, etc. You have to avoid their fire as well as keep them from killing the civilians before you can rescue them. You aren't defenseless however... You have at your disposal a machinegun with unlimited ammo which is good for the bazooka men, as well as missiles and bombs which can be used for tanks and jets. Ammo for the bombs and missiles are scattered throughout some levels, usually giving you enough ammo to easily take out all of the enemies.
When you have eliminated the enemies in an area you can land your helicopter next to a civilian, and they will run into your helicopter for safety and transportation. You can then continue picking up passengers until your capacity of 6 is full, and drop them off at your base. If your helicopter explodes while you have a civilian inside, that civilian will die, which hurts your score. If over half of the civilians on the level are in your chopper when it explodes, you lose and will have to start the level over. But if only one or two die in the crash, you will return to the beginning of the level to try and rescue the remaining civilians, however you will lose a life.
The level is finished when you rescue all of the live civilians and return them to base. Killing enemies provides bonus points, but you are not required to kill them.
If you lose all of your lives, the game is over and you return to the home screen. There are no saves or continues, so you have to beat the game all the way through in one sitting, old school style.
The graphics are surprisingly good for a freeware game. It is a 2d scroller, but it uses a combination of 2d sprites and 3d models to give a great sense of depth and speed as you progress through the levels. The explosions are big and realistic looking, the animation is smooth, and it's simple enough to run on an older G4 or G3 system. There are night missions, rain missions, snow missions, etc. to always keep the terrain varied and interesting.
The controls for Chopper are as follows:
Arrow keys - Movement (up down left right)
Space - Fire machine gun
S - Rotate chopper 180 degrees
D - Drop Bomb
F - Fire Missile
P - Pause
I found the controls to be well laid out and very responsive. You can rest your left hand in the "home row" position, like you would when typing, and control the whole game without moving your hands around. There is no lag at all in any of the controls, and it's easy to make fast dodges and maneuvers when avoiding enemy fire.
The sound effects are fairly generic, but are used sparingly enough that they don't get boring or repetitive.
The music is varied and upbeat, and provides a nice little soundtrack to the game.
The game crashed on me a couple of times, but I was having other apps crashing at that time also on my Powerbook, so I think it was my machine rather than the game. I also played it on my eMac and it was rock solid on that machine.
Overall this is a great little freeware game, and is a great way to spend a lunchbreak. It's easy to get into, but challenging enough to warrant quite a bit of practice even to beat the game on the easy skill level. It's definitely worth a download, even if it's just for nostalgia reasons. I hope to see a lot more old games remade with this quality in the future.