You may not remember GameSharks, but those things did you exactly what you suggest. As do most game cheat engines. Editing the state, directly in RAM, without the program's knowledge.
The next time something tries to use whatever memory or function it overroad, it would pick up your version instead.
There is a difference between a series of instructions that maps to machine code nearly directly, and a data format like an image, or factory templates.
The point about algorithms stands - it's not that programs don't contain any because a machine interprets them. I'm referring to the simple fact that program code can be expressed as a flow diagram - but try doing that with a CAD file. You can't, it's declarative in nature, not a series of steps and decisions.
The next time something tries to use whatever memory or function it overroad, it would pick up your version instead.