You dont rework the game.
First off download the program called Cheat Engine (Also get IDA but not for now!)
Then find a single player game (Please do not try multiplayer games because they are hard enough for even semi pro people sometimes!)
After that open the game up and attach Cheat Engine to the game.
Now a really easy way to start is if the game shows your health in text like (100 / 100)
You then search for your health.
You will now see there are so many results but that are too many results so what you do is you go somewhere and take damage and then type the new health value in and then click next search and you will then keep going like that till you hit <10 (Under 10 results are probably what you find for the most part) results.
Now you can take one of these results and then edit the value to like 5000 and see if it change in-game.
If you then try to get hit again as one of the results are the UI aka the number and not the real health.
If your health goes right back to your old value - the damage taken then you changed the UI value.
Try another result.
If this does not change the UI then its okay but try to get hit and see if the value return to the old value again and if it doesnt then its probably the right one.
Now if you close the game and you dont delete the address aka result from the list and then open the game again and attach again then it will probably show up with "??" because this is a fake address.
Now find the address aka your health again and now you need to find the static address.
The way you do is doing pointer scans (Look it up in YT).
When you find an address that is green that is a static address which means you probably found the right address if it holds the right value aka your player health.
Now that you got the static try to restart the game and keep the address in the list and attach again.
If the address value shows up as your value aka player health then you found it! (Good job!)
Now to use these in a program you make yourself you need to learn coding.
I use C# which is not the so called right coding language for creating cheats/hacks for games.
BUT you can use whatever you want as long as it can do read and write to memory!
Hope this helps you out and remember to look it up on google if you need help and if the game is too hard than take another game that is old so its easier than the new games