As always, champion balance
I immediately gravitated to the perceived strong champions; in particular, most of my early TT games were played with Jax. I've heard a lot of people say that various champions are too good in TT, especially Darius (who gets hate regardless of whether he deserves it or not) and Teemo (which is crazy).
TT's map design puts a large emphasis on map control. Teemo (and other characters with traps) can exploit this by placing them in commonly traveled areas. Before the recent Zed patch's changes to Hextech Sweeper, Teemo would reveal any opponent who hit a mushroom, and the unique ammunition mechanics of his ultimate gave him a lot of leeway in placing them. Even with the change, Teemo can still see whether his mushrooms are destroyed and identify the position of an enemy. It's just a little less obvious now.
Shaco boxes and Nidalee traps are also pretty good at giving jungle information, but it's not possible to deploy as many of them as Teemo can deploy mushrooms. The ammo mechanic is really very valuable in that regard. Shaco and Nidalee are still good, though, and I suspect we'll see more of them in the future.
Bruisers of various types, or "tankyderps," as they are often referred to, are very nice on TT, where there are fewer characters to deal damage and fewer characters to act as barriers to the enemy. Darius is a strong bruiser, so he sees a lot of play. Jax is also fantastic. Other bruisers do well; I've seen very strong Riven play. AP bruisers like Diana and Swain are especially strong because of the presence of the new item Blackfire Torch. I'll refrain from raging too hard on this item because I'm sure it will be nerfed, but it makes Teemo and Singed godlike and other mages very strong. I suspect that Ahri is pretty good on TT because of the Torch, but I haven't had much success with her (because I'm kind of bad with Ahri).
Assassins also work well simply because of the map's emphasis on roaming, but assassins who cannot clear lanes or jungle simply lack the ability to get gold, much as on Summoner's Rift. Mobile characters with high burst damage and good laning are great choices, in my opinion. I recently unlocked Diana and have been practicing her as much as I can, and her good mobility, reasonable survivability, and high burst-damage (combined with good use of BFT) make her very dangerous.
In general, I think a character needs to have either good laning or fast, sustainable jungling to be viable on TT. It's mandatory to get farm, and you really can't rely on duo laning in this mode; you really need someone jungling when the camps are up or you lose out a lot. I don't think Smite is necessarily mandatory, though. In fact, because you have only three team members, losing an extra Ignite or Exhaust is kind of a big deal. Smite does help a lot, especially with stealing jungle, though. It's one of those things that I'm not sure about just yet.
The roles and positioning
Twisted Treeline is very weird because the lanes are so long that any over-extending can result in brutal ganks. You need two laners who can hold a lane pretty well on their own; I like to think of each lane as a weird hybrid of Dominion's bottom lane and SR's top and mid lanes. Both lanes want to freeze the lane slightly inside their own zone of control, and I think at high level it will mostly result in freezing in the middle. It is so horrible to overextend into the enemy zone that pushing hard is bad, but getting pushed back can mean lost gold or experience or even a potential aggressive play.
Jungling is a bit different in TT than in SR since there are only three camps. The jungler serves as the gatekeeper to his altar area; in an ideal world, nobody would pass the speed shrine in the middle of the map without his knowledge. It's vital that the jungler be aware of any aggressive movements into his space, and he must react to any missing enemy laners. It's very easy to have enemy laners vanish for only 10 seconds before all three opponents are in your jungle.
Playing TT well involves balancing jungle roaming and ganks, team invasions into the enemy jungle, and farming. Farming is so incredibly important because the lanes are huge and stalemates at turrets are likely to go on forever. I recently fought a losing battle during which we still managed to hold the enemy at our turrets for over 30 minutes, even though we constantly lost battles to jungle invasions and had no altars captured. Amusingly, we eventually won by turtling at our last turret. Turtling is pretty strong in TT mostly because it's harder to push a turret down with three people than it is with five.
Because farming is so strong, the jungle invasion metagame becomes relevant. While most people go straight for the altar (and it's a pretty valuable target to go after), I think this is a mistake because even stealing a few jungle creeps puts your team ahead in gold and XP. Going after an altar will force a teamfight, and if there's any question about whether your team can win, it's better to just steal some jungle creeps and back out before the enemy knows you're there.
Likewise, you never want to let creeps get to your turret without someone there. The lanes are long, but I find that people still want to let the turret clear waves and go for a gank instead of getting the guaranteed gold from the minions. Always defend those turrets and go for that gold; gold is what gets you ahead in TT.
On the other hand, well-placed ganks and invasions can result in a 3v2 situation very quickly, and a 3v2 is a practically guaranteed altar (and an ace if the enemy tries to defend it). The key to going for altars is being up a player, I think.
So far, I've really only scratched the surface of strategy in TT, so I'm going to keep playing and keep practicing. Hopefully you guys will too!
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