There already are discussions about a category called "low%" where the player beats the world with every level finished with 0 coins, 0 badguys and 0 secrets. In 0.5.x Icy Island it's possible to do so, except of course for the Yeti who counts as 1 badguy.

In other worlds or versions it doesn't seem possible, so another way to look at it is that players can take the amount of collectibles they want and they will be ranked in ascending number of collectibles taken (and by quickest time for a same number).

Either way, for the category to exist, a devoted runner has to do a run of it ^^ I've been planning to run low% Icy Island 0.5.1 for a long time but I have other projects right now, so if you're willing to do the first low% run, here are some tips:

1. Dying resets the collectibles count. Low% relies almost entirely on dying to checkpoints, that means that you actually need to collect a lot of coins (dolls are useful) before a checkpoint to be able to respawn at the checkpoint.
2. Powerups are allowed because they're not counted. However, they're only useful (speaking for 0.5.1) to damage boost across enemies you can't avoid.
3. Some enemies, of whom are mostly bouncy snowballs, kill themselves in the void. You then need to be fast enough to make it despawn before it dies.

That's all I guess ^^ I've worked a lot on low% so if you need advice ask me here or on Discord.

I like this idea.