If an endeavor begins either not producing enough tangible results, requiring too much effort, taking too long, or costing too much, that's usually an adequit ground to abandon said task and move on to something more productive.
n. software that is no longer sold or supported by the original publisher / developer, often found as free downloads on the internet because it cannot be obtained elsewhere. Not legal, but often seen as morally acceptable because the company that made it is no longer selling the title, nor releasing it as freeware, therefore abandonware is "keeping the gamealive", so to speak.
Doom II is not abandonware because idstill sells it, while The Incredible Machine is not sold, therefore is abandonware.