Yeah that was me, sorry. I tried, for fun, to cheese my way into GM and it's entirely possible.
For example, one race of Starcraft has early access to a building that can fire upon enemies. If they can build these building strategically near an enemy's base without the enemy noticing, they can effectively box an enemy in, preventing them from expanding or attack until they commit a large enough force to destroy those buildings.
The same race in Starcraft can build permanently cloaked units that can only be detected with an "observer" class unit/building. If you can obtain the requirements for building said cloaked units without your opponent noticing and then build a few, you can send in these invisible units to damage your opponent until they have the proper response.
Basically, it's a strategy that can be overwhelming if it works, but it has a few tells and being discovered committing one of these strategies early enough is basically a loss.
It's usually very gimmicky strategy - for example building your barracks near enemy base at the start of the game and pumping army instead of workers, or attacking with your soldiers AND workers before opponent has army to defend.
Most players look down on cheese, cause it's much easier than to play a regular ("macro") game - you only need to learn a few first minutes of game and then either you won or you lost, you don't need to react to enemy, and you don't need to multitask much (you have few units and only one base at the beginning of the game).
On the other hand people say that cheese keeps others "honest" - people often play greedy (skip scouting and defense to get economy faster) and cheese punish that.
In tournaments when players play each other a few times choosing to cheese or not is another level of metagame.
If you defend against it, you pretty much win as they sunk all their resources into early low tier army, instead of economic balanced expansion.