If you want Little Nightmares 3 without the nightmares, Bumpkin & Sprout is the 3D Mario-style co-op platformer I need you to wishlist

Before I even sit down to play Bumpkin & Sprout at Digital Dragons, the poster has me hooked. As the eponymous heroes of Polish animation studio Rabid Rat's upcoming indie game, a 3D co-op platformer that can also be played solo, the mushroom duo's eco-mission is as simple as it is important: to clean up their forest and defend Nature herself from the Pollution Spirit's trash-spitting evils.

Before you dismiss Bumpkin & Sprout as a quasi-educational game for kids, think again. Rabid Rat presents a vibrant 3D world to explore either by yourself or with a friend, featuring platforming puzzles, hack-n'-slash action, and a combat-free map mode. Bolstered by a stunning handmade visual aesthetic, which you can check out for yourself on its Steam page, it was all too easy to lose myself in Bumpkin & Sprout's charming little demo – and for 30 minutes, I did.

So mush-room, so little time

Bumpkin & Sprout is a co-op game, but I'm relieved to discover that it's just as fun to play by yourself. Loading into a fresh save at Digital Dragons, no co-op buddy by my side, my first choice is to select a character.

I'm not sure which mushroom-capped eco-warrior is which, but I choose the younger looking fungus of the pair. Given the bearded "chin" sported by the other, pointy-headed mushroom, I assume I've selected the rambunctious little Sprout.

The symbolism of having one older and one younger protagonist isn't lost on me. Even without a wise caregiver at my side, it's a beautifully effective way for Bumpkin & Sprout to angle itself as a platformer for all ages – and it's probably a bit more appropriate for younger children than the unnerving likes of Little Nightmares 3.

But the warm fuzzies don't last long. As Sprout navigates his fantastical 3D environs, the cozy forest vibes soon give way to more serious conservationist themes. He encounters mounds of rubbish at every twist and turn, as well as patrolling impish minions sent by the toxic Spirit to disrupt Nature. For destroying the piles of trash I'm rewarded with power-ups, which float up in little bubbles from the detritus.

These vary from temporary traversal tools – like speed-boosting roller skates and an umbrella parachute, both used by holding the left trigger – to what I think must be health boosts (since my HP bar refilled inexplicably at one point) and other useful items that likely come in handy later on.

The same melee attack is useful against the Spirit's lackeys, each emanating toxic purple plumes as they march across the forest like Goombas in a Mario game. Instead of jumping on their heads, though, Sprout can march up and simply whack them out of the way. I eventually stumble upon a new way to attack my foes, however: a devastating ground pound, executed by double jumping and hitting the right trigger.

Growing together

Super satisfying melee combat aside, Bumpkin & Sprout's quirky level design is the real stand-out.

While exploring the forest and putting its smooth platforming opportunities to the test, I encounter plenty of inventive nods to the broader theme of ecology, each more adorable and clever than the last.

Interacting with a discarded tin opener unravels a hidden bridge, allowing Sprout to safely cross a sludgy river bursting with toxic waste. Elsewhere, a grimy toilet spews yet more filth. A discarded lighter becomes a makeshift hot air balloon, opening up the game's verticality as Sprout travels not only across the forest but up and down it, too.

These subtle quirks are a true highlight for me, identifiably connecting Bumpkin & Sprout to its core themes without being heavy handed about any of them. It's just one aspect of the consistently strong visual language that governs the game, from colors and their connotations to the symbolic nature of various setpieces, reinforcing Rabid Rat's expertise as 3D artists.

After 30 minutes of solo exploration, I still wish I'd had a chance to play Bumpkin & Sprout in co-op mode. I can only imagine how Rabid Rat has re-worked these nifty mechanics to accommodate two players, perhaps in the puzzle-solving vein of Hazelight favorites It Takes Two or Split Fiction. I can also see Bumpkin & Sprout's two-player functionality suiting the looser structure of something like Rayman Origins, one of the best PS3 games for local co-op shenanigans, right down to the colorful cast of characters in all their oddly-proportioned glory.

Either way, I'll be keeping an eye on Bumpkin & Sprout as it moves toward its unnamed release date – though next time I go hands-on with it, I'll definitely BYOB (bring my own Bumpkin).

Check out the best co-op games to play while you wait for Bumpkin & Sprout