The story is set amidst a battle for supremacy that has evolved into outer space with the world in chaos. There was a strong movement to unify the intentions of the people on Earth by establishing a government on the planet, while a dispute arose with those that migrated into outer space. When the government was founded, incidents of civil and political conflicts began from the world over. During these conflicts, one part of Asia was thrown into civil war as the nation was divided between those that wanted a unifying government and a monarchic army fighting for independence. The country was also as a prominent source of a powerful energy source called "neutron polymer", and fights broke out between forces with newly developed weapons and monarchic army gaining assistance from other countries. The governing side were attack by the opposing force's "Dread Tortoise", a giant battleship capable of transforming into a mobile neutron polymer fortress. After heavy sustaining casualties from the enemy, the government established an anti-battle corp of battle mechs, with three GUNHOUND soldiers — Eliza Taylor, Shin Ryuzaki, and Batisa Arbus Fisher — were dispatched in a battle against Dread Tortoise.
The gameplay of Armored Hunter GUNHOUND was heavily inspired by likes of the Assault Suits Valken series, however this game takes an aggressive arcade-styled approach of those games as players are encouraged to quickly dispatch enemies for higher score bonuses and each mission is under a time limit. Along the way, players can unlock various weapons as they accumulate score from their play sessions, ranging from machine guns, anti-air cannons, a flamethrower, a grenade launcher, and more. Players can also customize the look of their mech by changing the colors of its armor, or if they are looking for a greater challenge, remove the armor plating from their mech altogether.
The game was originally released in 2009 as a doujin PC game and is available through DLsite's Japanese page. It was later remade as Armored Hunter GUNHOUND EX, which was co-developed by G.rev and was released for the PlayStation Portable on January 21, 2013 with an upgrade kit for owners of the original doujin release for free. The remake features a retelling of the game's original story, updated graphics, a new soundtrack, and more unlockable weapons. The PC version of Armored Hunter GUNHOUND EX was released overseas by Active Gaming Media through PLAYISM and Steam in 2014. The story of Armored Hunter GUNHOUND EX focuses on a war between countries during the late 21st century in a search of a renewable energy source to expand modern society rather than a battle between Earth and space. When substance called neutron polymer was discovered, alliances were formed and quickly shattered between countries as they tried to get a hold of the resource. Veltonia, a small south-eastern Asian country, was caught in civil war when a concentrated deposit of neutron polymer was discovered, and soon became a world-wide battle. Juliane Yuri, Jason "Kid" Powell, and Commander Mikhail Karelin of the 9th Division Armored Hunter Unit "GUNHOUND" were sent in to quarrel the conflict.
Unfortunately, as of October 2018, Dracue Software has filed for temporary suspension and the EX remake of the game was also removed from all digital storefronts. The original Armored Hunter GUNHOUND can still be purchased from DLsite, but all of the game's patches were lost and servers connecting to the EX Upgrade Tool has been shut down due to the developer's dissolution. Prior to Dracue Software's suspension, the circle went onto develop a remake of Assault Suit Leynos for NCS, released on PlayStation 4 in 2015 followed by a PC version via Steam in 2016.
Armored Hunter GUNHOUND features examples of:
- Action Girl: Eliza Taylor in the original GUNHOUND and Juliane Yuri in EX.
- Arm Cannon: A Type-II example with the Gatling Claw, which gives you both a melee weapon and a Gatling Gun that nullifies bullets.
- "Blind Idiot" Translation: The English translation of GUNHOUND EX's menus and some of its in-game dialogue have some faulty translations. The menu descriptions in the Options menu don't give players clear information on what the settings do, and there is a typo on a few of the dialogues as well as an untranslated piece of Japanese text with Sophia's name misspelled as "Sofia".
- Boss-Only Level: The sixth and final mission in EX only consists a boss battle with William Wagner and the Gorgonossa.
- Charged Attack: The Anti-Ship Energy Cannon requires the player to hold down the sub-weapon button to charge up the cannon, but once it's full, it'll make anything regret standing in your way.
- Continuing is Painful: Although continuing the game after a Game Over wipes your score and locks players out of No Continue Clear bonus at the end of the game, the points that were earned during the run are added to the score counter on the title screen to allow players to continue unlocking weapons. Once the score counter is maxed out, however, your score during a run is no longer added to the counter.
- Cosmetic Award: Maxing out the score counter at 99,999,990 unlocks the Diver Antenna, which merely adds an antenna and fins to your Armored Hunter.
- Curtains Match the Window: Yuri, Kid, and Mikhail from GUNHOUND EX have matching eye colors that matches their hair colors.
- Denial of Diagonal Attack: Averted. You can aim your most of your weapons diagonally as well as above and below you.
- Difficult, but Awesome: Going into missions in your Armored Hunter's lightweight mode, which strips it of all protective armor, will leave you more vulnerable to damage and you can't replenish your Armor Meter by purging the armor without it. The trade-off however gives you better mobility, you can jump higher, and doubles the amount of points earned than equipping the armor.
- Escort Mission: Mission 2 has the Hound squadron escorting a supply raft carrying neutron polymer while protecting it from the enemy. If all of the neutron polymers containers are destroyed, Commander Mikhail calls off the mission and the player is greeted a Game Over screen.
- Fire-Breathing Weapon: The unlockable Napalm Thrower allows you to lay waste to your enemies with a stream of fire.
- Fragile Speedster: The Armored Hunter becomes one after jettisoning its armor. It becomes more vulnerable to damage but gains greater mobility and can land at any height without the shock absorbers slowing it down. Additionally, you can chose to go into missions without any of its protective plating with the lightweight setting.
- Game-Breaking Bug: The PC version of the remake has a bizarre issue with Steam Overlay and driver-based anti-aliasing, resulting in the game showing up as a black screen, even if the user isn't using any anti-aliasing whatsoever. However some users found that it can be alleviated by disabling Steam Overlay and forcing anti-aliasing to off via their video card's control panel.
- Gatling Good: Your Armored Hunter comes with two Gatling Gun variants from the start: a standard Gatling Gun that fires straight ahead, and a short-barreled Gatling Gun that fires at varying angles. The unlockable 30mm Autocannon provides a 3-way spread shot but has a longer cooldown period than the others, and the Gatling Claw gives you an arm-mounted Gatling Gun which can punch enemies as well as fire bullets.
- Gravity Screw: In zero-G areas, your GUNHOUND will rotate around the Left or Right button is pressed without using the Lock Aim button, and to change the direction your GUNHOUND is facing requires you to boost either Left or Right briefly.
- Homing Projectile: The Quad SAM Battery can lock onto targets and fire homing missiles that tracks locked targets. Some bosses are also capable of firing homing missiles of their own against the player.
- Inseries Nickname: In the original GUNHOUND, the three main characters, Eliza Taylor, Shin Ryuzaki, and Batista Fisher, are nicknamed Liza, Zaki, and Batsu respectively. In EX, Jason Powell is often referred as "Kid" as he's a rookie pilot in the 9th Division Armored Hunter.
- Kick Them While They Are Down: One enemy mech type can be attacked after being defeated and players are rewarded with extra points for each hit successfully landed.
- Laughing Mad: William Wagner in EX lets one out after his defeat in the final battle.
- Last-Name Basis: Juliane Yuri from GUNHOUND EX is usually referred by her last name throughout the game.
- Luckily, My Shield Will Protect Me: The Ballistic Shield obtained from clearing the all of the training courses allows you to block enemy fire. One of the enemy mechs also bears a shield that protects it from your attacks save for some melee attacks.
- More Dakka: Your Armored Hunter is capable of spraying enemies down with a hailstorm of bullets when equipped with weapons such as the Gatling Gun, the 35mm AA Cannon, and Gatling Claw. The enemies are no slouches either when it comes littering the screen with bullets.
- Mighty Glacier: By default your Armored Hunter is weighed down by the extra layer of armor that gives it greater durability at the expense of its mobility. Landing on the ground can also leave your Armored Hunter briefly immobile as its shock absorbers prevents damage from falling.
- Mission Control: Reiko from the original GUNHOUND assists the GUNHOUND troops during their missions, as does Sophia Pizzaro in EX.
- Palette Swap: In the Customize menu of EX, you can change the color scheme of your Armored Hunter's frame and armor to a few alternative colors.
- Power Fist: Your Armored Hunter's initial melee weapon is called Power Fist. It not only punches enemies in close-range, but can also punch bullets and missiles. Other variants include the Iron Claw, which automatically punches nearby enemies and enemy fire, a Gatling Claw that punches enemies and fire bullets, and the Clutch Fang, a powered up version of the Iron Fist.
- Rank Inflation: A title is given to the player along with the unlocked weapon after meeting certain scoring criteria, with the exception of the lowest rank of Trainee Graduate obtained for clearing all of the training lessons. Each title is based on military ranking, starting from First Class Officer at 3,000,000pts to Colonel at 99,999,990pts.
- Red Baron: In the game's online manual, Yuri has been referred by her enemies as "The Lady of Misfortune".
- Scoring Points: Destroying enemies and bosses gives players points of varying amounts, however points can only be earned as long as there is time left in the timer. The game sometimes provides the player a few opportunities to milk a few extra points from defeated enemies. There are other opportunities of scoring points, such as jettisoning your armor without taking damage, destroying the barricade in Mission 1 before the EM barrier is lowered, or protecting civilians during the extrication segments of Mission 3. By using the Armored Hunter's lightweight mode, players gain double the amount of points and armor pick-ups gives the player a 100,000pts bonus.
- The game draws inspiration from side-scrolling mecha games of the 1990s, such as the Assault Suits series and Front Mission: Gun Hazard. The game's presentation is also reminiscent to that of Assault Suits Leynos 2 as it uses detailed 2D pixel art and rotating sprites.
- GUNHOUND EX had a Super-Deformed demake in the form of Armored Hunter GUNHOUND Pocket, featuring Game Boy-inspired visuals and chiptune music.
- Sexy Santa Dress: A promotional artwork of EX features Yuri wearing a Santa top and short-shorts while Sophia wears a Santa dress. The artwork of Yuri was used in Steam profile background.
- Shrinking Violet: The manual of GUNHOUND EX mentions Sophia is shy when she's off-duty.
- Spread Shot: The Short-barreled Gatling Gun fires in a spray burst and scatters bullets while the 30mm Autocannon fires in a 3-way spread. The Shotgun also fires in an initial burst by shooting in a 9-way spread.
- There Is No Kill Like Overkill: If the Gorgonossa manages to grab your Armored Hunter after destroying its armor, it will hold you close to its wave motion gun and vaporizes you with it.
- Timed Mission: The entire game has a time limit in which the mission must be cleared in. If the timer reaches zero, the player will no longer be able to score any points thereafter for that mission.
- Video Game Flamethrowers Suck: Subverted with the Napalm Thrower. Despite this weapon burning though fuel quickly, it can tear through enemies in a hurry, and in the right hands, can make short work of bosses.
- Video Game Remake: Armored Hunter GUNHOUND EX features a retelling of the original game's story, updated graphics, a new soundtrack, more weapons, and the ability to customize your Armored Hunter's color palette. The PC version of EX also gives players the option to play the game in 60 FPS like the original version and features the ability to stream in-game dialogue to a smartphone by linking the game with a special smartphone app (Android and iOS, but only available in Japan).
- Voice with an Internet Connection: The dialogue exchanges between characters are done through radio communication. There was also an Android app (in Japan only) that allowed the game to stream the voice-over dialogue from the PC to the app over network.
- Wave-Motion Gun: Some of the enemy mechs in the second half of the final stage will a carry shoulder-mounted energy cannons that can be devastating if the player doesn't intercept their attack. The second to last boss, Daimian, will try and chase the player with a powerful laser beam. The final boss, Gorgonossa, is also equipped with a massive energy gun. The player can unlock one in the form of the Anti-Ship Energy Cannon after scoring a total of 30,000,000pts.