I came across a question a few weeks ago about the legality of using such software as Resource Hacker to change the Game.exe icon, so I thought I’d answer it.
First of all, according to the EULA:
Licensee shall not reverse engineer, de-compile, or disassemble the Software.
which means, in short, that technically it IS illegal, since you’re modifying something that is part of the "Software", i.e. RPG Maker.
With that said, however, you’re not actually directly modifying the software itself, only the game’s icon for creating shortcuts. And, since there isn’t an apparent option for the INI to use an icon, for some developers having a game-exclusive icon is a preference they don’t want to be without.
According to Archeia on Steam:
Technically it isn’t [legal] and Enterbrain is aware of it. But they’re loose about the rule.
In other words, Enterbrain doesn’t condone using software to hack Game.exe to change its icon (which is what Resource Hacker does), since that would be a violation of the EULA, but they are tolerant of it provided you’re ONLY using it to change the icon – and nothing else – and do NOT directly modify the software itself. This includes anything that comes bundled with the RPG Maker itself, the RTP software, Game.exe, and any accompanying DLLs.
EDIT: To clarify, Deciga/Eb! hasn’t "officially" given an answer on this issue; it’s just that they appear to be "tolerant" of it (only changing the game icon).
If you’re in doubt, don’t do it!
Instead, you might be interested in the How to Change the Game.exe Icon Tutorial for alternative methods that don’t directly modify or hack Game.exe.