UDO (which stands for “Unidentified Drilling Object”) is a pleasant little roguelike platformer developed by Blue Firefly Studio where you must survive while drilling into a deep pit on an alien planet. With the game going for a more stripped-down, arcade sort of experience, those looking for a more robust or varied challenge might be left wanting. Although fans of similar roguelikes such as Downwell and the more recently released Shovel Knight Dig will likely have a good time with UDO despite its simplified nature.

UDO sees you play as a miner on a foreign planet employed to drill deep into a creepy hole filled with aliens and traps. It’s quite straightforward and narrative-lite, even by the standard of most roguelikes, but the promise of getting just a bit farther in each run or saving up for a sweet upgrade is incentive enough to power through the game’s four biomes.

Similar to the aforementioned Downwell and Shovel Knight Dig, UDO is a platformer in which you are constantly moving downwards. Your miner automatically digs through breakable blocks below them, bouncing upwards as they go. You can also cancel your momentum and zoom in one of four directions using a rechargeable fuel resource, making switching between pogo-ing and strategically dashing through enemies, small openings, and treasure the way to go. Unlike the other two games, in UDO you can dig upwards from the start, making it a bit more forgiving regarding missing collectables or breaking blocks in the wrong order as you can just dig back the way you came, as long as you have enough fuel.

It’s a compelling enough little gameplay loop, really hitting its stride when you get into a nice groove of bouncing between enemies and timing your dashes correctly. Aside from passive equippable abilities, you also have access to limited-use items found throughout levels, including shotguns which fire pellets downwards and a short-range teleporter device. However, I didn’t get too much use out of them, either because they had too few charges to be useful, like the teleporter, or had such limited utility to not be worth using, such as the camouflage device.

The general structure of each of UDO’s runs doesn’t change much, with each run involving 4 main biomes with 3 levels each. The levels’ themes and order in which new enemy and hazard types are introduced remain pretty much the same across playthroughs, meaning that the novelty of the experience doesn’t last long. As such, the repetition sets in fairly quickly.

What does mix up the runs in UDO a bit is the addition of special abilities which can be purchased at the end of each level. These range from simple passive buffs like an increased maximum health bar or jump height, to weird and fun powers like summoning zombie helpers after a few kills or a random chance for a level to start with an invincible limited-use mech suit to carry you part of the way. Any ability you buy throughout a run is added to the store from which permanent abilities can be purchased, with the player able to equip a certain number of them from the start of each run.

Once you’ve bought all the abilities you want, you can also unlock new skins for your miner scattered throughout the runs. I liked the designs and thought that it was a fun feature (although the one with the glowing furnace for a head did defang some of the intended challenge in the darkly-lit second biome). The pleasingly simple retro-style pixelated art and bouncy chiptune soundtrack were enjoyable as well and felt very appropriate for the arcade platformer vibe that the developers were going for.