Alien Soldier

Alien Soldier is a side-scrolling run and gun video game in which the player controls the main character, Epsilon-Eagle, through 25 stages and 26 bosses. The gameplay has been compared heavily to Gunstar Heroes; however, putting a much larger emphasis on boss fights, and lacking any 2-player option. The stages are notably short, populated with weak enemies to serve as downtime between the more difficult boss battles. There are two difficulties in the game, "supereasy" and "superhard". Enemies on the hard setting are only slightly more difficult; however, there are no passwords or unlimited continues as in the easy mode.

Epsilon-Eagle can run, double jump, hover in the air, and use six different types of weapons. Only four can be equipped at any given time, but the player may choose which weapons they would like to equip before the game starts. Each gun has its own ammunition bar which can be replenished; if it is depleted the player will be left with a little firepower. The player can also perform a dash across the screen, which when at full health, will become a deadly move called "Phoenix Force" that will damage any enemies in its path.

The premise of Alien Soldier is provided with a long text scroll at the start of the game. After the game has begun, it is not referred to again. In the year 2015, the A-Humans of A-Earth have created genetically engineered A-Humans capable of super intelligence and strength, as well as parasitic co-existence with machinery and animals, particularly humans. A terrorist organization known as Scarlet rose up within this race and sought to dominate the rest of the A-Humans and A-Earth by locking the planet down and keeping anyone else out.

During the height of Scarlet's power, an assassination attempt on the group's leader, Epsilon-Eagle, was carried out by a special forces group. Scarlet fought back with their powers, and the battle somehow breached the space-time continuum. Epsilon was gravely injured and cast somewhere into the continuum.

After developing Gunstar Heroes, Treasure was divided into four teams working on separate projects: Dynamite Headdy, Light Crusader, Yū Yū Hakusho Makyō Tōitsusen, and Alien Soldier. Development of Alien Soldier lasted two years and was led by Hideyuki Suganami, who from the start wanted to make the entire game himself. Despite 32-bit fifth generation hardware already on the market, he chose to program the game for the 16-bit Mega Drive, claiming that he may have been too captivated by the idea of making an "action shooting" game which the system was known for. Treasure explicitly targeted the game for "hardcore" Mega Drive players and designed its difficulty and end-game scoring methods with this in mind.

Suganami described the game as "for Mega Drivers custom" and proudly placed the phrase on the game's title screen alongside a Mega Drive advertising slogan: "Visualshock! Speedshock! ".

For its original Mega Drive release, Famitsu provided Alien Soldier with a score of 24 out of 40. Mean Machines Sega called it "a real gameplayer's game", citing the unrelenting waves of enemies and high difficulty. They noted how Treasure was beginning to establish a pattern of good games, and called Alien Soldier a modern classic. Simon Clays of Computer and Video Games found it to be challenging and unique by basing its gameplay on boss fights. Other editors from the magazine complimented the boss design and animations.

Frank Provo of GameSpot reviewed the Wii Virtual Console release in 2007, citing the excellent graphics, sound, and general intensity of the game. He noted initial difficulty adjusting to the controls and game design. However, once accustomed, he said, "you start totally feeling what it must be like to be an army of one trading firepower with some of the universe's largest, most elaborate creatures. That's a great feeling."