Crossover:
Maybe, after a fashion.
Is this a 'My Life is a Video Game?!' fic?
Yes, yes it is.

Timeline:
Begins: After Harry's Death in Book Seven.
Continues from pre-Hogwarts Letter, Book One.

Alterations to Canon:
Game Mechanics, Dungeons, Reputation Scores, Quests...
Assume everything might be altered in some way, large or small.

Pairings:
Probably Harry/Hermione

Afterlife:
Harry commits suicide-by-Voldemort and his next moment of conscious thought he finds himself standing in front of the improbably white and sanitary Kings Cross Station. Only, Dumbledore isn't waiting for him, no parents, not even a four-legged Godfather trying to drool all over him... instead the 'Arrivals and Departures' board simply informs him 'GAME OVER'.

To Load a Saved Game - Board at Platform 9.
To Start a New Game - Board Platform 9 ¾.
To Exit from 'The Wizarding World' - Board Platform 10.
To View or Change Settings - Inquire at Ticket Counter.

More details appear on the board revealing his entire life, in the categories of 'academic', 'quest completion', 'relationship' and so on, summed up in school grades ranging from Troll to Exceeds Expectation. Total character points: 288. After raging for a bit Harry boards Platform 10.

PEVERELL ENTERTAINMENT LLC.
GAME-LIFE™ GAMING SYSTEM.
'Live Life Like It's a Game!'™

He is presented with a new menu and options but not one of them is an exit button, log-off or even 'summon the Boatman'. Opening the Store however reveals a variety of other 'games' available to be purchased and played.

Do take the opportunity to obliquely reference other fandoms/media, if only for shits and giggles, i.e. 'Hell's Doorstep: Sunnydale', 'Winter is Coming' or 'These are the Voyages'. The thought of playing another game, another life is briefly considered until he sees that his account balance, §7.50, won't cover a new one. Apparently these Simoleons are earned through unlocking content and achievements in his existing games.

Checking his Library reveals an interesting development... there's DLC for his existing copy of 'The Wizarding World - Vol I: Headed for Hogwarts'. Reading through the options, more Quidditch matches, bigger Hogsmeade and more weekends, expanded magic system, elections for a student council, additional NPC content and interactivity, Harry begins to realise how... incompletely scripted his last life seemed to have been.

A massive castle like Hogwarts and he'd only been inside the few classrooms where lessons were taught. Only 30 or 40 students per Sorting, an entire year's worth of magical children for the entirety of the UK? In fact he'd barely interacted with 5% of the student body in 7 years. One shopping district? One magical township of a dozen streets, maybe 100 houses? Hogsmeade weekends... no one's parents came to meet them, just a floo trip away? He couldn't recall knowing anyone whose family lived in Hogsmeade... how did that make any sense?

Did his previous life come with 'new and improved suspension of disbelief'?

Amongst the DLC is a free upgrade called 'Hogwarts Uncut - 17+ Only'. Reading the details makes Harry's head spin... nudity, profanity, sexuality, euphorics and gore all had been restricted to a limited minimum without this DLC. It was like some children's fantasy story book. No wonder he'd died a virgin.

Seeing no other choice and hoping he can just go back to what he knows he buys the DLC that interest him the most and chooses to play 'The Wizarding World'.

Rowling Productions: Let's Make Some Magic™

There are no saved game files and figuring he might as well check it before he starts a new game he goes to the ticket counter to look at the settings. Game difficulty: Hard. What a big surprise! Harry dials that back down to Medium, which enables limited game save options. Ethics Code? Oh, look! Nudity, sexuality, profanity? Yes, please. Game Manual? Merlin... Harry reads the game guide and learns all about the mechanics and metrics and how it all works.

STR, DEX, VIT, INT, WIS and CHA.
Reputation and Relationship values and tables.
Skills, Crafting, Achievements, Perks, Flaws.

Beginning a new game by walking through the column to reach Platform 9 ¾ he finds himself prompted with a 'Create Character' menu. Not being some Malfoy peacock he doesn't tweak his personal appear much beyond making himself a little taller, 'cause being a shrimp sucked. Assigning his stat and skill points was agonising but at least he got some free ones earned based on his performance on the previous game session. Then comes picking perks... and flaws.

Fledgling Flier, granting an initial 20 skill points to Flying, a +10% XP modifier to the same, +2 DEX per level while aloft on a broom and additional Reputation gains from actions involving Flying skill tests. Sounds a lot like what he had last time around, but perhaps not the most useful perk for fighting a Dark Lord.

There's dozens of flaws and perks to choose from, some even sound familiar: Semi-Second Sight, Magical Merchant, Besties with Beasties, Metamorphmagus, Mental Gymnast, Gambling Man, Ugly Duckling, Tone and Rhythm, Potions Moste Potent, Sorcerer's Apprentice, Somewhat Squib, Like a Sloth, Where's My Remembrall?.

Taking two flaws means that along with his one free perk he can take a total of three.

To his surprise his Skill List is already quite populated but spotting the rather well-developed Cooking, Gardening and Cleaning skills makes it clear that these are the skills acquired from his childhood at the Dursleys. Sciences, Reading, Writing, Mathematics he no doubt got from his schooling. Stealth, Athletics, Unarmed Combat and Pain Tolerance unquestionably from Dudley's favoured pastime 'Harry hunting' and the so-called tender affections of his Aunt and Uncle. Parseltongue... how was he supposed to get the horcrux out of his head if an AK to the face doesn't work?

The real surprise comes when he selects 'Start Game'.

Allocating to Server.
Server #17 has [19/25] Players queued for Game Start.
Placing player in stasis, awaiting full server occupancy.

Reality flickers.

Stasis suspended. Duration: 819,191 seconds.
Reinitialising... Server #17 has [25/25] players queued for Game Start.
Game Start in:
60

There ARE other players... people, so that means his friends might be playing too!

Playing at being his friend... like he is playing at being Harry Potter. It only occurs to Harry then that his entire identity stems from the character of a computer game and that, possibly, he's about to get over-written by a new back-story. No amount of panic seems to halt the countdown though.

NPC characters rendered, scripted and initialised.
Cartographic and topological overlay implemented.
Clipping completed for Hogwarts wireframe.
Merchant transaction system implemented for Diagon Alley.
Fixing waypoints for Dungeons.

24, 23, 22...

His second thoughts become third, fourth and fifth ones but there's no Back button available now.

13, 12...

Disassociating memory context from previous sessions, now.
Populating character memories with back-story, now.

5, 4, 3...

Harry couldn't wait, this was going to be so much fun.

START.

Outline:
1) Thanks to that last twist Harry isn't aware his life is a video-game, per se. He certainly doesn't remember his previous 'play through' or the game set-up, manual or other realisations. That doesn't mean that all gamer aspects disappear though. Going to be tricky, Time Travel + Amnesia doesn't often add up well but having all foreknowledge makes Harry to OP.

2) Changing his perks, flaws and character stats means that Harry's own pre-Hogwarts back-story is changed just a little. Picking more intellectual power, for example, making him more insightful or picking more charismatic capacity could change how he is treated by the Dursleys. He should start his do-over just prior to Dudley's birthday, so just like the books, not from age 5 or some such - otherwise the story might never get to Hogwarts (other Gamer!Fics have made that mistake).

3) Harry should at least be aware that some 'Game Commands' exist. As part of his back-story he accepts that he became aware at some point that he could say [Display: Time] to get a pop-up window showing him the time and date and that looking at something and saying [Observe] would pop a message giving some information about that object.

4) Harry ought to learn to see his own Status Menu before he goes to Hogwarts. A possible basis, for example, this time around Vernon or Petunia see and realise that Harry is talking to snakes at the zoo and in a fit of superstition 'beat the devil' out of him and Harry uses [Observe] on himself for the first time (to check how much Durability he has lost) and sees his character sheet. HP, MP, stats, skills, grimoire, equipment and so on.

5) Periodically in the story, by some plot contrivance or repeated event (i.e. deboarding the Express at the end of a year) Harry should automatically be booted from the server to the Game Menu while server maintenance is undertaken and so he can receive his previous memories and evaluate his progress, the changes, purchase additional in-game DLC or skill-packs or some such.

6) At some point Harry has to learn, see or discover that other people have the same talent that he does, i.e. they are playing their life like a game, the other 24 players. Pick them to be who you want... but Voldemort should be one of them, so that he plays this play-through at least a little bit differently as well.

7) Every main character should be a little OOC to reflect the new play-through theme. Perhaps there'd even be a couple lesser (probably not main) characters gender-bent where someone is now being reprised by a player of the other gender. Deanna Thomas? Marcellus Bulstrode? Silvia Kettleburn? Blaise Zabini (wouldn't be the first time there, lol).

8) Hogwarts should be filled with assorted zones and dungeons. Different parts of the shore of the Lake, a zone once a player is deep enough under water, where the Selkies play, the Grindylow kelp fields, the Merperson's village. The actual dungeons of the castle should be a warren of corridors leading to boggarts, doxies and other indoor magical pests and creatures (feeling free to modify some traditional video game creatures for a Hogwarts setting, i.e. slimes). The grounds and the forests should have rock outcrops, caves, burrows, canopy, streams and pools and a lot more other various magical creatures occupying these habitats. Some of those '1000 Magical Herbs and Fungi' should be found throughout all these zones and be harvestable. Crafting of drops from magical creatures and those gathered herbs should be possible.

9) Harry and the other non-NPCs ought to be able to party for adventuring, quests, combat and so on.

10) It is a school so don't neglect the opportunity to make acquisition of good marks and performing well on tests grant bonus overall XP, skill progression or other rewards. It'd probably be best if learning a skill from a book isn't just the cliché click [Y] and the book disappears in a flash of light and a new skill is created. That would mean actually having to balance between spending time grinding on adventures and on acquiring skill progressions from reading and studying. Some perks and flaws would, of course, aid or hinder gains from one or the other.

11) Too much math isn't fun for anyone. It's appreciated when it helps make sure that the progressive growth in the skills and power of a character are justifiable but not if the story becomes a litany of: A did X amount of damage to B. It's story-telling after all, find a balance.