is an open source tool designed to help you with modifying single player games running under window so you can make them harder or easier depending on your preference(e.g: Find that 100hp is too easy, try playing a game with a max of 1 HP), but also contains other usefull tools to help debugging games and even normal applications.
It comes with a memory scanner to quickly scan for variables used within a game and allow you to change them, but it also comes with a debugger, disassembler, assembler, speedhack, trainer maker, direct 3D manipulation tools, system inspection tools and more.
For new users it is recommended to go through the tutorial(The one that comes with Cheat Engine
, you can find it in your programs list after installing) and at least reach step 5 for basic understanding of the usage of Cheat Engine
Cheat Engine Website - Cheat Engine