Okay, to elaborate a little bit more: "high level play" in roguelikes these days usually means speedruns or challenge runs. Of the two types of roguelikes I outlined earlier, the second (BoI/Risk of Rain/Spelunky) is far more popular for this than the first type. Of course randomness plays a large role in the outcomes of these speedruns/races/challenges, but the trick is using sufficient knowledge of the game's nonobvious mechanics to help overcome this randomness and "play to your outs" as best as possible. Which is, I think, what Grefter was asking about.
Before even touching on this, though, it is important to make clear that all this type of play is not aimed at the new or casual player who is just playing the game 1-10 times and putting it down. All this content and all these concepts are aimed at people who are deeply into these games and spend a lot of time playing them. Like
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Youtube personalities who do full runs with in depth commentary every day-
Streamers who marathon games nonstop when they come out, for up to two weeks, with literally no breaks, until they 100% the game, and only then return to a "normal" schedule of streaming it for 4-8 hours nightly-
Speedrunners who do multiple daily attempts at 3+ hour marathon all-character runs- That's just Isaac, you want some Spelunky, how about Bananasaurus Rex, here are some links:
https://www.youtube.com/user/FlyingToast303/playlists http://www.polygon.com/2013/12/23/5227726/anatomy-of-a-spelunky-miracle-or-how-the-internet-finally-beatNow a lot of the folks here reading this are probably going "lol yes if you're a super obsessed ultra minority grinder, but who cares about them?" Obviously the above are all very extreme examples, but they are not alone or as extreme as one might think. The Steam global achievement stats for Binding of Isaac Rebirth show the rate of users getting into the final unlocks to be around 2 to 5%. (2% for True Platinum God, aka Absolutely Everything including the really tedious grind bits, 4% for Godhead, the hardest "skill" achievement involving beating everything with the OHKO character on Hard, and a bit over that for completing some of the OHKO character's unlock branches.) 5% sounds like a low number... but count the number of people you know who play these games and think about even one in twenty of them being into "hardcore" play. The original Binding of Isaac sold well over two million copies according to Wikipedia, and while sales stats aren't available for Rebirth, it's not at all unreasonable to imagine it's broken a million already. Five percent of a million people, or heck, half a million, is still
a heck of a lot of people interested in and engaging with roguelikes in these ways.
So let's talk in depth about Binding of Isaac Rebirth, since it's currently the most popular game of this type by far. Isaac is an easy game to beat. As Fenrir noted, even a relatively non-hardcore player can enjoy ~100% clear rates when taking their time and using the stronger characters. But trying to play quickly, in a race or speedrun situation - that changes the game significantly. There are a few items that can "break" normal progression and enable fast wins right from the start of a run, but they're relatively rare. On the other hand, there are much more common items in certain categories (Curse Rooms and Devil Deals) that are closer to, I dunno, 20-30% reliability at putting the player on the fast track. If the game was all about resetting for Polyphemus in the item room that would be one thing, but it's not. On average, or in a race situation where resetting counts against your overall time, it's better to accept a "just decent" starting item and then try for some of the somewhat reliable routes.
Curse Rooms have a high rate of appearing on almost every floor, and a low to moderate chance of containing either soul hearts or one of the Guppy items. Not taking red heart damage highly increases the chance of getting Devil Deals, which can contain gamebreaking items, or Guppy items (three Guppy items breaks the game), or more soul hearts. Soul hearts help ensure you don't take red heart damage. Mapping items can shave significant time off a run, and are found exclusively in shops, so it is good to get $15 if possible to buy them if they appear. That's just a super bare bones primer but you can already see how there exist many possible avenues of reinforcement and good habits that will on average produce significantly faster runs and higher success rates than just rolling the dice on the starting item room.
We can go even beyond that, though. Roguelikes are randomly generated, but they are rarely truly random. Map generation engines for these games have patterns, they *have* to in order to produce playable areas, and with enough experience humans can pick up on these rules, either explicitly or subconsciously. Spelunky speedrunners can look at the first bit of a level and tell the path to the exit with about 95% accuracy. Isaac isn't quite so kind from a starting position, but it's still good enough that the Map is effectively also the Compass for telling where the boss is. Diablo 2 runners... well, most of them maphacked back in the day, but the folks still playing no longer need to, and there are some code dissections floating around out there if you care to look. The randomness can be gamed, and for a decent subset of players like myself that is absolutely fascinating.
