This is easily one of the saddest games I've ever played. Not sad as in "gripping story", sad as in "they actually thought this would make money, bless their little hearts". Nearly everything about this game is done poorly, from the interface to the controls to the effects to the voice acting (ESPECIALLY the voice acting).
The game's plot, such as it is, is delivered via laughably bad translated text, spoken haltingly by the single voice actor for the game. There is at least justification for each mission, but truth be told the game would be better off if there WASN'T. The plot is so thin it may as well not be there, and frankly is embarassingly crappy.
Speaking of that voice acting, the one person they got to do voice work for the game either has no acting talent, a poor grasp of the english language, is 12, or all three. In addition to the pre-mission text, the same actor also shouts out random "taunts" and "reactions" as you play. I put those in quotes because they are all delivered with all the emotion of a plank of wood. Not only that, the random barks are translated just as badly as the main text, leaving us with taunts like "take that terrorist dog". There's very little variety, and the taunts/reactions happen frequently, so get used to hearing "see you later alligator" delivered by a heavily tranquilized teenage mental patient a million times.
As for actual gameplay, it's pretty bad. Your main weapons is your basic gattling gun, though it seems to cut out randomly; I'm unsure if its because of poor control implementation or some sort of overheat system that isn't displayed on screen. You have two banks of missiles you can choose from, but they do barely any more damage than the gattling guns, and the difference between the two is not obvious and is definitely not explained. In fact very little in this game is explained other than "shoot things and sometimes it extends your time". Random pickups float in the world, corresponding to mechanics that you can only guess at based on their icons. Picking up these items results in bright, flashy effects that signify seemingly nothing, and half the time you can't even pick them up for reasons which (again) aren't explained. You weapons do a varying amount of damage, seemingly at random, sometimes mowing down enemies in quick succession, sometimes taking 2-5 seconds just to take down a basic grunt. Targeting is entirely automatic and picks up far too slowly, leaving you with no way to dumbfire at enemies you know will be coming from the top of the screen.
Beyond the gameplay though, the rest of the game is pretty annoying too. The menu screen is a constantly revolving and zooming view of a helicopter, set at a speed juuuuuust fast enough to make you slighty queasy. The configuration options are confusing, using non-standard button names for gamepads, particularly 360/XBO controllers which should have native Windows support, though to be fair the options are rather detailed within that. The biggest problem though is that you are required to enter your serial key for the game literally every time you start it, and sometimes randomly when you back out of a sub-menu. On my first launch I started the game, entered the serial key, configured my control options, then was prompted to enter my serial key AGAIN. Oh, and as a bonus, it refused to accept my serial key the second time. I wound up having to restart the game entirely.
In short, Heli Heroes is a hot mess. There's some basic enjoyment to be found under there, but the overall system is too clunky and confusing to make that an easy task. You may need to consume a great quantity of alcohol to find this game not annoying, and even then who knows. Quite honestly you will find a more robust and rewarding helicopter game in something like Tiger-Heli for the original NES, because at least that has consistent controls, reliable gameplay, and no repeated requests for a serial key. Do not waste your money or time on this game.