Yes, you probably did it 300 hours ago. The world doesn't revolve around you, you know.
Diablo 3's end-game starts at level 70, the current cap. It's here that Adventure Mode opens, bringing with it the ability to use green set gear and the best legendary items, and enter the realm of the infinite Paragon levels. If you're looking to bury the rest of your days in the prettiest spreadsheet in gaming, your initial goal is to hit 70.
I took a Crusader from 1-70 last week in about 19 hours which, I now discover, is about 600% longer than possible (provided you've already completed certain tasks). Based on my trip through the story, and coupled with advice from other players, here's how to get to 70 with the minimum of fuss.
1 - Boosting
Boosting is by far the most effective way to level in Diablo 3. The concept is simple: you team with a benevolent high-level player (or players) who's vastly over-powered for your game. They do the work, you clock off the levels. My Battle.net buddy Darkfield, a long-time VG247 reader, joined me for Act IV and Act V of my Crusader run and turned my struggle into a walk. Being level 70 with a 500+ Paragon level, Mr Darkfield is able to one-hit almost everything on Torment I difficulty, meaning all I had to do was follow his wake of destruction, pick up the loot and watch the XP rise. Your experience will move every time anyone else in the party kills something, provided you're on the same map. If you're looking to get to the cap in the shortest way possible then speak to anyone you know who's already achieved a high level. Be warned: you won't be "playing" much. If you don't care and just want to get to the good stuff, this is the fastest way to do it.
2 - Rubies in helms (and the importance of saving gems)
If you're in the market for XP, you should know to keep your eyes out for socketed helms. Inserting a ruby gives you an XP boost, the level of which can be large depending on the gem involved. A Marquise ruby, for example, will boost your XP gain by 33%, meaning for every two levels you're getting one for free. Inserting any ruby into a helmet will give you an XP boost.
On the subject of gems, don't sell them just because you don't think they apply to this specific run. Keep everything. All those daft little jewels you keep picking up can be combined (for an increasingly significant charge) to create more powerful stones. You'll probably be dropping most of your gold on combining gems, as they can have a huge impact on the effectiveness of gear. You won't if you don't have any to combine, obviously.
3 - Build guides, Elective mode and understanding your class
Diablo 3 is a big game. Not only are you able to pick from five classes, but near-infinite variations can be applied to your skill set-up. Each skill is customisable with runes which unlock as you level, giving access to different effects and behaviours. If you don't have at least a basic understand of your class and its concept, you're going to find enemies harder to kill. That means less XP per hour and slower leveling.
You should take the time to read a little about your class and look at some sample skill set-ups. Articles like this one on Icy-Veins may look like gobbledygook to the novice player, but you'll find truly invaluable information here on how your class's skills and gear can work together for maximum effectiveness. You won't have access to a lot of the stuff recommended if you're just starting out, but you will get a good idea of where to head with your selections.
The Crusader's a good example of the power of knowledge in Diablo 3. By just doing a cursory bit of reading I realised that aiming for a straight DPS build was a mistake. The Crusader's an archetypal tank, meaning you need to focus just as much on armour and health as pure damage. Your high level friends won't be around all the time, so make sure you understand your class and how to manipulate it to your play-style. The more effective your character, the more successful your play, the faster you'll level.
While we're here, you should know about Elective mode. In its default-set-up, Diablo 3 restricts each key on the hot-bar to a single set of skills. If you want to have full customisation of which skill goes where (and you will), hit Esc > Options > Gameplay and tick Elective mode. You can now map any skill to any key.
4 - Halls of Agony Level 3, Act I bounties and setting your difficulty
What you're essentially doing here is XP farming, so you need stuff to kill. Halls of Agony Level 3 has the highest density of monsters of any level in the game, so if you want to level as quickly as possible this is where you do it. Once you've opened this level on the map, just start a new game, run it to the boss (the advice in this video is to not even kill him as you don't get enough XP for your efforts) and as soon as you're finding you're running about too much and there's little left to kill, you start doing Act I bounties (because the enemies are the easiest to beat). You'll only be able to access the bounties if you've already cleared all five acts on another character and opened Adventure mode. If you haven't, just quit the game, make a new one and hit Halls of Agony Level 3 again.
You'll need to set your difficulty correctly to maximise the amount of XP you're getting per hour. The recommendation there is to go for Hard. You want to be able to one-hit most enemies and spend only a few seconds on elites. Watch the video for a better explanation. The narrator reckons you should get to 70 in somewhere between 3-7 hours.
This may be a quick way of leveling, but it's more for those trying to get Seasons characters to 70 as quickly as possible as they'll already have access to the Adventure mode bounties. Running a single level over and over again may be effective, but it's always dull.
5 - Skip the story
If there's a single way of speeding up a Diablo 3 run it's by skipping the story. Sure, watch it all once and listen to the voice acting, but when you're hitting the campaign for straight leveling just press escape on the cut-scenes and close down the VO conversations as quickly as you can. I don't want to spoil anything for you, but Diablo gets it in the end. If you've heard one evil laugh you've heard them all, if you catch what I'm saying.