Game-Breaker / Game-Breaking Bug - It used to be possible to run on an unlimited number of stolen computers before the humans begin to react to your presence on Day 22. This is no longer the case (except on easiest difficulty level); you can only have 10 bases at the same time without human interference.
The "Autonomous Computing" and "Advanced Quantum Computing" technonogies, and the quantum computers they unlock. One third-gen quantum computer has more computing power than two large warehouses of first-gen quantum computers combined. This won't make you invincible, but once you build them, you can research most technology topics within hours, sometimes minutes. Down Played in that it doesn't grant you immunity but "merely" takes care of most of your CPU and cash issues.
The Scrappy: Some research topics, like Advanced Arbitrage, which merely adds to your interest rate, or Advanced Database Manipulation, which merely gives you a "covert base" option, which is too much a Master of None (computing and hiding capabilities are both very mediocre).