Played through the NERF World in Minecraft Bedrock Edition. I liked it quite a bit, actually, but I have a few complaints with it. The most damaging blaster in the game, the Ender Dragon, is also horribly unreliable, which makes crowd control a pain. Crowd control is important, of course, when the game is choosing to spawn your enemies pretty much right next to you anytime new mobs spawn, which can lead to you getting beaten to death by mobs of mobs really quickly with little warning and no recourse in some rounds.
There's a part of me that wonders how it would go in co-op; this isn't necessarily a single-player world, it's just how I played it because none of my other Minecraft-playing (Bedrock or otherwise) friends were online at the time. This world is free, you can claim it on the Marketplace right now and play it for yourself if you want to. In fact, consider inviting me along for the ride. I want to see if the rounds are any easier with an extra person shooting. lol
On the other hand, it might take longer to unlock all the blasters in co-op, with the currency potentially getting spread around to each player individually, so I suppose that can wait until at least some of the blasters are unlocked. In any case, I recommend giving it a try.
EDIT: Turns out the currency is in fact shared! And yeah, co-op makes everything better!