a fusion of 'by accident' and 'on purpose' meaning to accidently do something on purpose. To acknowledge that ones actions were deliberate whilst at the same time claiming there was an unintentional component β in other words a feeble plea of mitigation.
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.