Kivi's Underworld is an isometric overhead camera point-and-click adventure, telling the story (at least initially) of Kivi, a fighter with some backstory behind him, accessible at any time through the interface. The demo only lets you play as Kivi, but other characters are available in the purchased game

The first thing you'll notice is that KU plays like Diablo, but with a few notable exceptions. First, the camera is focused in a lot more closely, providing a viewpoint that doesn't show as much of the surrounding terrain as Diablo did. Similarly, there is a Fog of War-type of darkness that surrounds areas that haven't been visited yet, and once visited, these areas open up. The Fog is also visible in the minimap, shown in the upper right corner of the screen.

Left-clicking moves Kivi to the point of the click, and holding down the button lets you walk Kivi around without stopping. Left-clicking also attacks enemies, picks objects up, activates your powerups, etc. The right-click is used to activate your default, more powerful attack, which eats up a chunk of mana.

You'll come across several locked doors in the environment that can only be opened with the properly color-coded key. The key is usually tucked away somewhere in the heart of the dungeon, which necessitates some backtracking to return to the locked door. Also along the way are several destructible barrels, within which you'll find precious stones and gems, coins, and health or mana potions. Most barrels take just one hit to destroy, while others might take two. Barrels might also contain powerups, which are one-time use only, and are stored in one of three slots to the left of the interface. Only three can be carried at a time, so it's important to choose wisely, though of course you can always return to pick up items left behind.

It's worth noting that the health and mana potions are used immediately upon pick-up, and Kivi regenerates both resources fairly quickly (at least on Normal difficulty level), so the only real time you'll need them is when being set upon by a horde of enemies at once.

There are secret doors that open to reveal further rooms and passages, but at least in the first few levels of the game they're not terribly difficult to find, being colored somewhat differently than the rest of the walls. Each level is finite, as are the number of roaming enemies, so it's worth finding all the hidden areas to be as complete as possible, and get as many points as you can.