Basically. survival friendly, but regenerating flares.

The player begins with a 1 flare of a random color on spawn. To change your flare color you craft them like the survival flares, however you only get 1 of the color, however they are not thrown in this mode as an item, they are equipped or added to your maximum.

When you rightclick you equip the flares instead into your regenerating flare slot. Each flare added increases the maximum of regenerating flares available at max. The "regenerating flare count" becomes regenerating flare max to cap how many someone can get total.

Flares remain as the last color you equipped.
or alternatively a button can be used to cycle your flare colors from colors you've crafted and equipped before. If you're at flare cap and you craft a new color, you can equip it to unlock the color, but your flare number won't increase further than the cap.

A random mode would also be selectable and you'll throw flares chosen randomly between those you've unlocked similar to the setting in the video I saw.

Death optionally be set to reset total flares and/or drop a bundle of them in the colors you owned, for that kind of gameplay if one desires.