Are Game Trainers legal ?
The simple answer to that question is YES, they are 100% perfectly legal. However, there are some cases when they could be considered illegal or could get you in a lot of trouble.
Cheating or using them in Single Player Games:
If you are using trainers in single player mode, then they are perfectly legal. Trainers are actually memory-modification programs that modify your games memory to give you the desired effects such as health, ammo, easy kills etc. You are free to modify your computer memory however you like so since trainers only modify memory, they are 100% fine.
However, modifying game files is NOT legal, depending on game EULA. Most games do not allow that so you can get in a lot of trouble if you modify game files or use software that modifies it.
Using Game Trainers in Online / Multiplayer Games or against other human players:
Technically speaking, this type of hacking or cheats are not illegal by function since you are modifying your game memory here again as long as you aren't modifying game files. However, cheating in this mode, you spoil the game for other players, players which are real humans and NOT computer A.I.
This rightly is condemned by game companies and is what they mean when they talk about cheating or cheaters. This as i understand is illegal, since most game EULA explicitly mention it and the penalties that may come with it.
DEViATED Gamehacking also strongly discourages this type of cheating and/or using our trainers for this purpose. Our trainers are never tested or made for Multiplayer part in mind and while they may work if the game has no or bad cheating protection for online gaming, we can't be held responsible for your actions or if used online.
So the bottom line, the game trainers you find on this site are 100% legal and perfectly fine to use!. Use or abuse them as you wish.