Spolier: Do not put 'listening to leftists' as your answer, too easy.
With the paracite hangers on of game 'journalists' the first to go, the amount of bleakness from Ubisoft, EA trying to sell itself harder than a crackwhore, we are approaching a point where we may end up with only 3-5 major ones left and a few focused on one title that's been around for decades (eve online, your DOTA games etc).
Doesn't really affect us as I think I'm safe in saying we all have backlogs that can outlast us being on Earth! So why not make this a fun opportunity to go 'you know, if you did this , you wouldn't be begging for money'. Choose whichever companies you want on what you think was a missed opportunity:
EA: Not using their IPs together enough. Seriously how hard would it have been to make a Battlefield game set in the Command and Conquer Red Alert or Tiberium franchise or even do a sports game but in the backdrop of Mass effect. They seemed to be all about processing IPs than using them effectively.
Bethesda: not using an Id engine for Fallout 4. When I played Rage, the story was lackluster but the combat and gameplay was smooth, fun with fantastic visuals. Unless there was a hidden licensing reason, why not use THAT for Fallout 4, that seemed like the perfect engine .
Nintendo: making it too difficult to buy and play older titles so creating a piracy market.
Microsoft: not letting gamers be the one to design their military AR project as they could've probably told you the dumb parts quickly.
Sony: Not embracing Japanese game devs, not leveraging their monopoly on anime with PS+ by doing, for example, free first 3 episodes of a series on Crunchyroll if you have PS+. Also on Crunchyroll, just put an adults only section for uncensored anime, have it behind a paywall of some small fee and a SECOND password and you'll probably get a lot more subscribers.
There's more I could mention like Ubisoft, Rockstar, CD projekt etc but gone on too long and let this be a collective 'I would've done this' thread.
oi, i dont think i can really settle on one but i will do my best. i think the biggest mistake in general was the corpratization for lack of a better word of game studios as they grew and hired staff they gradually listen to their internal staff more then their fans as a result they gradually loose touch with them, on top of that you have foul things like marketing and other executive meddling that alter the game and a corperations goal is to make profit so of course they are going to go public bringing in the vultures to take yet more control from the company and those that made it. eventually the people that make it split and your left with a bugman in a skinsuit that cant create their way out of a papper bag hiring based on chckboxes and quotas with their design process being similar resulting in a product that has little soul if any inside it but thats fine your buddys at game site 9000 will spin up hype and promoted results anyway for early acesses and other favors,