Stop That Roach!

Hoi Hoi (ホイホイ) is one of the earliest non-historical games made by Koei, produced by Kou Shibusawa. The game's namesake is a brand of glue traps used to trap cockroaches in Japan, not the definition found in contemporary slang regarding fascination with a particular object, subject, or person.

A remake of the title was made for the Game Boy, which diverges from the presentation of the original game. The player's goal in either version is to protect confectioneries from various cockroaches. The Game Boy version was localized as Stop That Roach! in North America.

According to Koei's company timeline, the first version of Hoi Hoi won first prize in Obunsha Publishing Co.'s October 1983 Personal Computer Rankings.

FM7 Version
The player can choose to play as a business man, a housewife, or a student. The business man is overall balanced while the housewife has the most life and the student the best intelligence. Rooms are displayed with a hexagon grid, each object or person utilizing a single hexagon. Blue areas marked on the screen are the available for the player's movement; red areas are restricted. Action is turn based, the cockroaches moving only once the player has decided on their plan of action.

When facing the "army" of cockroaches, the player may strategically place hoi hoi (glue traps) to stifle their advance. Multiple hoi hoi can be stacked on a single tile yet a single hoi hoi can only stop one cockroach at a time.

Alternatively, the player has the choice of moving next to a cockroach to beat them back. They must arm themselves by equipping themselves with the slippers and spray cans placed on the map. Each "weapon" can be used multiple times once gained, yet they have a percentage limit marked at the left side of the screen. The character type determines how long each weapon can last before it breaks. If a cockroach is on the item's hexagon, the player will not be able to use it.

Cockroaches progressively grow in numbers as the player progresses, similar to most tower defense games. The player can check their progress by reading the cockroaches' angry text responses at the bottom of the screen. While the game plays a lot like a war simulation, it has a cartoony and light-hearted touch to it.

Game Boy Version
The player can choose between two characters, a young boy named Ken and a young girl named Lilly. There is nothing to differentiate them, aside from their sprite animations. Rooms are now displayed as squares and characters move in one direction on square tiles. There are 100 stages in the game, a password may be given to players to continue from where they last left off (each ten levels). The goal is to defeat every pest in each stage.

Ken and Lilly are given a limitation of five actions per stage. They can move five blocks per turn, shout and jump to scare cockroaches within two blocks, use a weapon or choose to do nothing for the rest of their actions. Weapons characters can use include a slipper, a bug spray, and a broom. A slipper attacks cockroaches in one space, a spray destroys groups, and a broom hits two blocks and scares nearby cockroaches. Ken or Lilly can only attack in the direction they are facing; they cannot target anything outside of their line of vision. These are limited in number and should be used sparingly.

Hoi hoi (glue traps) appear after the first ten stages. This time, they can trap multiple cockroaches and can be rotated and positioned by players in specific blocks. Hoi hoi are placed before the player character's own actions so it's best to scare or trick the cockroaches into them.

A cockroach's behavior is determined by a number of factors. If there is food within their sight, they will prioritize on the closest or the one in front of them. Otherwise, they have a tendency to crawl within a straight line or near walls. Cockroaches are also sensitive to nearby attacks and may head to whatever direction they're facing as a result.

With these changes, the game abandons its simulation aspects to instead be like miniature brain teasers. Cockroaches can react to the player's actions and will automatically win if they aren't defeated within five turns. Each stage is designed to test the player's critical thinking skills in order to win, and become gradually harder and trickier to solve. If the player is completely stumped, they may choose to pause the game and view the automated answer to move on; this option will not always be available on later stages.