Strikingly animated indie co-op shooter Cuphead was revealed at E3 in 2014, and was playable at the expo a year later, but little has been seen of it since.

Now, in an interview with GamesRadar, brothers Chad and Jared Moldenhauer have outlined why the game has taken so long to complete.

It turns out the brothers and one other were only working weekends on the game, which prior to E3 2015 was simply a boss rush bullet hell shooter.

However, after those at E3 expressed disappointment that there would be zero platforming and that they'd only be battling bosses, StudioMDHR made the decision to expand the game's scope to something more akin to the game's influences – Contra and Gunstar Heroes.

That meant the brothers had to quit their day jobs, re-mortgage their houses and expand the dev team.

"This was our chance to actually deliver the game we wanted to make all along, rather than the cut-scope game we originally planned with a three person team," said Chad Moldenhauer.

"The reality is, Cuphead is closer now to the game we always wanted. We aren't throwing levels in to mollify people, we're putting them back in after originally cutting them from our ‘dream scope’.”

Even with increased manpower on board, Cuphead's hand-drawn animations are time-consuming to create.

“We don't use any of the modern techniques or software tricks to assist our animation," said Chad Moldenhauer.

"If you see an egg spin 360 degrees in Cuphead, we didn't draw one frame and spin it in software, we drew all the individual frames at each stage in its rotation.

“We can't just move a hand up 30 pixels or squash a head down 10 pixels, the whole action has to be redrawn from scratch.

“This means we end up doing a ton of planning and iteration before anything gets to that level, as we can't afford to throw out a lot of work… Even something that seems simple, such as the flower enemy, has over 100 frames of animation.”

According to Moldenhauer, this style of animation allows for greater creative freedom.

“We can stretch and squash characters in fantastical ways or do crazy or wacky things that a more grounded style wouldn't allow,” he said.

“It pretty much opens us up to do whatever we want gameplay-wise, because thematically, it'll probably fit.”

Cuphead will finally release on September 29 for Xbox One and PC. Now we just need Capy to nail down a release date for awesome-looking but similarly-delayed roguelike Below.