Marketability of certain gameplay formulas and level setups all factors into sales. The more good things people have to say about your game, and the wider its appeal, the better your publisher can sleep at night - but that might not be the game you're making.
Mixing challenge, cross-genre appeal and your own artistic vision is a tough balancing act to get right, and we've seen the industry evolve to become more cinematic than ever. The dawn of 3D and more interactive play-spaces means genres are less defined than ever, yet we're always going in expecting certain tropes or levels of quality.
Whether it be chasing difficulty spikes or introducing elements intended for wider appeal, there has to be a cohesive whole emerging throughout, especially once we've reached the credits and can reflect back on what worked and what didn't.
So, from crowbarred-in frustrations to sporadic tonal-shifts built to appease the masses and everything in between, what are the most jarring and worst levels of the decade so far?
16. Priority: Palaven - Mass Effect 3
The more EA got involved with Mass Effect 3's development, you can just imagine how the pitch meetings went - "Yeah, you've got your universe all sewn up, but where's the shooting?!"
Alas, Bioware caved and slapped a whopping great turret sequence inside the Palaven level, setting a tone that pleased wayward action fans who'd perhaps wandered into the series otherwise sci-fi-heavy tone, whilst royally peeing off everyone else.
A turret sequence, in a Mass Effect game?! Sadly, yes. You strap in, hold down the right trigger and point the screen at a few waves of Geth. Woohoo.
Fallout 4 adopted a similar structure at its beginning, too, immediately throwing you into an action-heavy set-piece with a minigun and some Power Armour, eliciting much the same reaction from its fanbase.