U-Boot Ausflug is a small action game playable using any internet browser. Move your yellow craft using the cursor keys, and collect the air bubbles released by the white objects. To play, simply click on the small button on the lower left of the screen.

Your bubble count decreases whenever the yellow craft collides with one of the floating objects. A short cutscene will occur once you've acquired a certain number of air bubbles.

Uberleben is a hotseat party game with support of up seven players on keyboard, mouse and joypad. In it, participating skydivers must attempt to reach the ground safely by navigating around obstacles while collecting rings to increase their mobility and attack strength. The space key can be used to restart a level quickly.

Uchu Force is a decent Star Force clone, featuring enemy sprites drawn with only two colors. Use the mouse to move your ship around, and hold the left mouse button to shoot.

Options and power-ups can be collected to increase your firepower. A boss encounter is introduced occasionally.

Uchuforce 2 is perhaps the most accessible shooter by Babarageo after his memorable STG Banner, supposedly inspired by the classic Star Soldier series. Collect the letters to spell the title and earn an extra ship plus weapon upgrades. Losing a ship means a weapon downgrade.

Press the left mouse button to activate your lasers, and use the P key to pause the game. Lasers will overheat after prolonged use and requires a short period of inactivity to cool down.

Uchuusen (Spaceship) is an arcade game that puts you in control of a ship with two rockets attached to each side, and by selectively activating the thrusters you can navigate around tight corridors and obstacles in this twenty-level challenge. Fire both thrusters and the ship will float upwards, and collect the shiny yellow objects to unlock the portal to the next area.

It takes roughly fifteen minutes to half an hour to beat all of the stages included, and at the end of the game you will be presented with a results screen charting the total time and retries attempted.

Uchuwars is another shooter developed by Babarageo using Flash, featuring power-ups and bombs in addition to standard boss encounters. A full screen mode is available by clicking on the link found above the description text.

The first few levels are not particularly fun to play but the game does get better once you arrive in space. Continues are allowed, just click on the stage or power indicator at the main menu.

UFO: Alien Invasion is a squad-based tactical strategy game in the tradition of the old X-COM PC games. However, the game is neither a sequel nor a remake of any X-COM or other commercial title. UFO: Alien Invasion has two main modes of play - Geoscape mode and Tactical mode.

In Geoscape mode, the game is about base management and strategy. You manage the activities and finances of PHALANX, controlling bases, installations, aircraft and squads of armed-response troops. You'll research new technologies and use their results in battle against the aliens. You'll launch your interceptor aircraft to shoot down UFOs and dispatch dropships in response to alien activity across the globe. You can build, buy and produce anything you like, as long as your technology level and your budget will allow it.

Geoscape mode employs easy-to-use time buttons to control the passage of time however you like, automatically pausing whenever there's an important message for you to see. Research will progress and items will be produced as time passes.

In Tactical mode, the game is about taking command of your team in various missions to combat the aliens wherever they might appear. Each soldier gets a certain number of Time Units, representing the total time they have to act during the current turn. All actions in Tactical mode require Time Units to perform. Once a soldier is out of Time Units, he or she can't do anything more until the next turn.

Your mission objectives will vary for each mission, and there are many to perform as the aliens' terrifying plot unfolds. You'll have to watch your back, be quick on your feet, and take the fight to them.

The game engine is based on a heavily modified version of ID's Quake2 Engine. This doesn't mean that UFO: Alien Invasion is a modification or even a total conversion of Quake 2. It is a stand-alone game and doesn't require Quake 2 or any other program to run. All you need to play UFO:AI is a computer running Microsoft Windows or a supported version of Linux.

The updated engine has modern OpenGL graphics and special effects, increased texture resolution, hardware-accelerated clipping of map layers for toggling between levels, a new animation system for player models, powerful artificial intelligence, and many other features.

UFO:AI also supports cooperative team play with multiple players on both sides, up to a maximum of 3 teams for each side, 6 players total.

Ulitsa Dimitrova tells the story of a seven-year old boy named Pjotre who lives in St. Petersburg, running around the streets and doing things that young children of his age are taught not to do.

There is no inventory to manage nor an objective to achieve, but the game does end if you let it idle for a couple of seconds.

Ultimate Bruce Lee is a remake of the Commodore 64 platformer with updated graphics, new gameplay modes, unlockable extras, and the original 1984 release recreated faithfully to please fans of all things retro. You assume control over the legendary martial arts master on a quest to retrieve the elixir of immortality hidden deep inside a wizard's fortress. This will involve collecting lanterns, jumping over traps and defeating numerous evil minions as you make your way from one room to another.

Use the cursor keys to move, duck and jump. Press the Z key to strike at an enemy. Collect all lanterns from the first three screens to reveal a hidden passage to the next area.

Ultimate Vengance Power 4: The Lemon of Justice is an experimental game submitted by Sophie Houlden for a recent Ludum Dare competition, in which developers must create a playable prototype and post their hastily-made project on the site in less than 48 hours.

Use the cursor keys to move the protagonist around, and grab as many stars as you can for points. Press the Z key to jump, and tap the X key to shoot.