Hack9 is a Cave Story mod which requires some knowledge of the Japanese language to play, featuring a storyline unrelated to any of Pixel's creations.

Use the cursor keys to move, and press the Z key to jump. Tap the X key to shoot when you've acquired a weapon. The status and inventory screen can be accessed using the A key. Choose the first option from the main menu to start a new adventure, or select the second line of text to restore a previously saved game.

Hacker's Digest is an arcade game with puzzle elements, in which you have to guide an orb into a glowing blue circle to complete each stage. Features sixty stages categorized into six different difficulty groups, from easiest to near impossible.

Halloween House is a game made by Magnus Nilsson for a Halloween game competition. Use the shift key to access your inventory, and press the control key to interact with objects. The game can be saved by accessing the computer in Michael's room.

Halo Zero is an excellent action game in the style of Contra and Metal Slug series, with a little Abuse thrown in for weapon aim. Play the role of Master Chief as you partake in more dangerous missions, but fear not all the weapons from the original has been translated faithfully to the 2D version.

The sprites are large and closely resembles their counterparts from the hit FPS, animation is smooth and you can actually drive a warthog in the game. A recommended effort if not for the use of licensed characters.

Haritama is a fast-paced vertical shooter created by replicorn, author of the Pipe Dream remake Pipeful Sunday. The game comes with an auto-bomb option, which can be enabled in the settings menu.

Use the cursor keys to move, hold the Z key to shoot, and press the X key to launch a bomb. Reducing your desktop resolution before starting the game helps to increase the display window.

Harmony is a first-person shooter game made by Thomas van der Velden. It is inspired by 3D shooter games from the nineties like Doom and Duke Nukem 3D. Harmony uses the free Zdoom engine, which was made to mimic and enhance id Software's Doom2 engine.

The game features high resolution sprites and eleven maps to play in total.

The new release from Double Jump Studios, Harmotion sheds all the unnecessary baggage for a versus gameplay in which real-life opponents face off against each other for a spot in the top rankings.

The first power-up collected is used to search for opponents online, though players are advised to modify the Windows firewall setting before running the executable. Collect red power particles to increase your firepower by holding the right mouse button. Tap the left mouse button repeatedly to shoot at your opponent or disintegrate the plasmoids. The tab key can be used to display your current stats, while pressing the enter key brings up the chat interface.

Your opponent always appear at the top of the screen. Each ship has it's own advantages in a battle, and it's up to the player to choose one that suits their preferences.

Harpooned is a Cetacean Research Simulator disguised as a vertical shooter, in which you play the role of a Japanese scientist performing research on whales around Antarctica.

Hazard - The Journey of Life is a 3D exploration game that features a host of creative puzzles to solve, but contains no real danger or enemies in sight. You begin in a room called the HoloChamber, which acts as a central home that you can teleport to using the escape key at any time. The map on the wall shows the rooms which you have explored previously, and you can click on it to activate a teleporter that sends you to that location immediately.

The mod requires both Unreal Tournament 3 and the 2.0 patch installed before it can run properly, but it is definitely worth going through all the trouble just to play this one-of-a-kind experience.

HDOS Databank request 01 is basically a remake of Tetris Attack's Puzzle Mode (Panel de Pon in Japan), where blocks are removed by arranging three or more matching blocks in horizontal or vertical lines. This is achieved by swapping two blocks at a time, but be mindful that the number of moves allowed per stage is always limited.

Careful planning will be required to solve some of the latter stages, especially when the only way to clear the entire screen is by chaining multiple combos from just a handful of swaps.

There is a video walkthrough here for the first twenty levels, but referring to it basically spoils all the fun (or frustration) to be had from figuring out the puzzles yourself.