[The Fifth Horseman]

:/ That question shows you have little to no idea about programming or reverse engineering.

* If you want to code a new game (even if it's a remake), you are free to pick any programming language you want.
* If you want to mod the assets of the existing game (or allow your remake to load them), you will have to reverse engineer their formats.
* If you want to alter the existing executable, you will need appropriate tools. IDA Pro is one of them - you'll also need an IPS patch generator plugin for it, there is one but I don't remember where to get it - and the set of tutorials going by "Lena's reversing for newbies" will teach you the rest.