For instance in Counter-Strike 1.6:
Crosshair placement was key when navigating around a map. Good crosshair placement meant always having your crosshair in the optimal position to where an opponent would more than likely have their head at as you came around a corner. I noticed that this same mechanic really relates to rally points in the same way. That having a bad rally point is like having bad crosshair placement. You want a rally point that takes into consideration any possible opponent interceptions of your units. A good rally point will take heed of these possibilities and not cut. A good rally point doesn't let AI call the shots and isn't the fastest route (according to the AI) to utilize. For instance if you are on Metalopolis and you spawn horizontal to each other. There is an engagement between you and your opponent going on and you took the high road to get to your opponents natural expansion. It is a distinct possibility that if you rally all your barracks, for instance, to a unit in your army, that the AI will decide the quickest route to get to reinforce your army is the low ground. However since your army only cleared and has control of the high road and not the low road this leaves an extremely high probability open to being succeptable to having each and every one of your reinforcing units intercepted. Instead take the few extra seconds to instead of rallying your barracks to a unit in your army, rally your units through the actual path your army took to get to where it is. It will lead to far less interceptions of your reinforcing units (especially against a Zerg opponent who is favoured to counter attack you down the path your main army did not take). Again rallying your units incorrectly is like running around in Counter-Strike aiming at people's feet haphazardly. It's just asking for trouble.
Fake-defusing a bomb that had been planted was an antic that got more popular as time went on. Basically the idea is to assume your opponent is somewhere in range of hearing the defuse sound (which is a reasonable assumption to make considering if you defuse the bomb you win the round, and there is no logical reason why a player would allow you to win the round) and not really proceeding with the defuse so that you can intercept your opponent unwittingly coming out to see if you are defusing or not. It's more or less a passive-aggressive tactic that gives inclination for your opponent to react aggressively. And obviously there is plenty of equivalents to this in Starcraft 2. For instance feigning an attack and falling back. It's hard to think of others off the top of my head but I know there has got to be more (if you can think of some feel free to share them with us).
Checking corners and spamming spots could definitely be lumped into the equivalent of scouting in Starcraft 2. Whereas using sound itself would definitely be the equivalent of spotting in Starcraft 2. And there is an really eye opening way of thinking of scouting if you don't think it's the most important thing in the game and for some of those FPS genre players that came over to RTS as Starcraft 2 being their first game. Think of scouting and spotting in this relative manner in terms of importance from the RTS to FPS genre. Not scouting with your initial, standard 9th harvester, and not spotting the map with Xel'Naga watch towers is like aiming straight down at where your feet would be in Counter-Strike 1.6, or any FPS game, with sound muted, and hoping that you can get from point A to point B without getting shot in the process. It really just isn't too likely. You're going to lose to a competent player if you don't scout. Ever since I've thought of scouting that way it's definitely because the most important thing to me ever since.
Something many players used to was on eco rounds where the players did not have the funds for riffles or anything of much else they would try to compensate for this by hiding in annoying spots and corners and hoping you wouldn't check it (whether by looking directly at it or spamming it). Day9 would slap them for hope-based play and I laugh back at it now because players generally only sat in these types of spots on rounds where they knew they didn't have the funds to afford riffles. And since most players had an understanding of the money system in Counter-Strike 1.6 any competent player would know which rounds those would be. And low and behold, the rounds that you can't afford to buy anything where the rounds they checked those spots. But strangely, even at a top level, it began to slide if it wasn't one of those rounds and players hid in those spots and suddenly began getting away with it. Apparently it's like saying people only would scout if they had a reason to scout. Which is broken logic because you should always scout otherwise how can you be prepared for any amount of possibilities. I think a bit of it was laziness in players not checking corners on rounds they weren't expected to be there. And other times it was just obliviousness to the fact that not everyone plays in a 1 dimensional fashion. All of this in how it relates to Starcraft 2 just makes me think of someone hoping their dark shrine doesn't get scouted and it's in the most common proxy position on Earth, and further hoping that he doesn't have detection by the time you get there. Hope based play, Counter-Strike 1.6 is full of it and desperation. Would have made Day9 sick.
Shoulder peeking was pretty common where a player would only show as much as him that was necessary to check an area of the map in a quick strafe peek. I can see this kind of being echoed in Starcraft 2 in several ways. One of the most common examples being when people have 1 zergling just scout for a millisecond what is going on at the front of the opponent's ramp to their main base on map like Metalopolis against a Terran opponent. Shoulder peeking was also much a good way to bait out a player towards you. In Starcraft 2 I see poking and prodding actually being used to bait players into a trap all the time (especially when baneling mines are involved).
Counter-flash setups were used a lot by teams. Most of these meant you were sacrificing map control of what you would normally have and play an area of the map for retake. You would lure the opponent into a false sense of security, blind them, and retake an area of the map aggressively clearing out anyone foolish enough to step into the area you were prodding for an opponent to walk into. In Starcraft 2 I am still trying to think of just how this would relate in terms of a direct mechanical view. I mean all I can think of in terms of relative equivalents is how some players used to do forge fast expand openings with full wall-offs, which sacrificed early map control in turn for the forces to take it back later on more quickly. But I'm sure there is a better example of how it relates to Starcraft 2 because as I try to think I can't really think of any ways in Starcraft where you can sacrifice a large amount of map control, and instantly take it back as soon as your opponent comes in rage of what you sacrificed, and be actually able to punish them for it (other than a generic answer like flanking).
Boosting was always used as both a way of being randomly aggressive and to better assume a defensive position. I can definitely see how units like warp prisms and collosus getting to spots normally inaccessible can be both useful for offense and defense.
Multi-pronged attacks were pretty prevalent at the top level. The thing with multi-pronged attacks in Counter 1.6 metagame was though, usually the majority of the multi-pronged attacks were a bluff or feign for at least 1 of the 5 players to slowly clear the way for where the team was really going (unless by chance in the middle of the bluff the round falls into their lap because they actually pick off enough players at the area of the map they had no real intentions of taking). Most players back then called this 'working picks'. I can see the correlation with multi-pronged drop attacks especially. You aren't trying to end the game (usually) with it but you are just testing the waters while you hide your true intentions beneath the open, visible aggression. Again this kind of goes back to the whole idea of, if someone is playing aggressive, they probably have something to hide or defend. In Counter-Strike 1.6 it was much the same way. Players would poke and prod and purposefully make all the noise in the world while 1 or 2 players clear out another part of the map slowly and meticulously (yet not committing) while the majority of the team is distracting and spotting for any kind of counter-aggression to catch players off guard and out of position from. If such fortune came their way they would immediately continue pressuring the side of the map where the pick was made, and usually just leave 1 player to continue flanking quietly while the rest of the team began executing a take somewhere.
And of course from good ol' Quake 1 from when I was a kid:
If you get a Quad Damage, it's pretty much the same as double forge +1 upgrades finishing. You have a good advantage for a timing attack for a short time. But the longer you wait, the less of an advantage you are going to have until eventually, poof, it disappears.
But yeah as of late I've just been thinking of what exactly could ever mechanically be applied to Starcraft 2 from competitive experience from Counter-Strike 1.6 and so far a good chunk has been applicable (whether directly or indirectly). But of course RTS and FPS are completely different genres. They're not exactly the most likely canidate for complimenting jigsaw pieces that will fit nicely together.
So again have you guys ever made any connections from what you may have learned from competitive experience of a different game (that could even be a completely different genre) to Starcraft 2?