Every hundred years, the insect swarms emerge from their caves, and the Queen Centipede awakens. Every hundred years, a hero is chosen.
This time, the chosen hero is Wally, a simple bean counter. He may not be the usual hero, or a hero at all, but he's going to have to make it happen.
This game contains examples of:
- 1-Up: Little sunburst collectibles occasionally spawn in the levels, and award an extra life when collected. You also receive a sunburst-thingy for every sub-objective (rescuing Wee people, defending buildings, etc) maxed out in a level.
- Anti-Air: One of the subweapons available is a red rocket that launches into the air and homes in on airborne enemies. A few worlds in, an upgraded green rocket starts appearing as well, and towards the end a yellow super-rocket appears.
- Book-Ends: The opening cutscene of level 1-1 ends by saying "when you're asked to save the world, you don't ask why — you just make it happen". The end cutscene of the final level says "The battle was fierce, but Wally just made it happen."
- The Chooser of The One: The opening cutscene of level 1-1 shows that the hero is selected by a "magic stick" — a forked rod with what appears to be a compass on it.
- Collateral Damage: It's possible to accidentally shoot and destroy Wee people and buildings. Buildings can typically take a few hits and stay standing, but people go down in one shot.
- Embedded Precursor: Arcade mode, depending on the release, is either an emulation of the original arcade game, or a recreation of it with Adventure mode's graphics.
- Every 10,000 Points: Extra lives are awarded every 6,000 points.
- Homing Projectile: The Anti-Air rockets will home in on airborne enemies if there are any nearby. How well they home depends on which rocket; the red one is pretty clumsy, the green one is better, and the yellow one can turn on a dime.
- Invincibility Power-Up: The aptly-named "Invinciblity Shield" gives the Shooter a blue force field, protecting it from almost all damage for its duration.
- Mutually Exclusive Powerups: The shooter can only have one type shield at a time — trying to pick up an Invincibility shield while a Ladybug shield is active, or vice-versa, will do nothing.
- Notice This: In the Dreamcast port, powerups are surrounded by a field of sparkles, to ensure you can see them from far away.
- One-Hit Point Wonder: As in the original game, taking a single hit will instantly destroy the Shooter — unless it has a ladybug shield, of course.
- Protection Mission: One of the most common sub-objectives in a level is to protect buildings in the area from the invading bugs.
- Sequel Hook: In the end cutscene, the narrator says "you should see what happens every thousand years". The answer would presumably have been shown in a Millipede update, though no such game was ever released.
- Shout-Out: The first boss, Ant May, is a pun on Aunt May.
- Single-Use Shield: Ladybug shields give the Shooter two extra hits, and can be stacked up to three (six hits total), as indicated by the number of spots. This was nerfed in the PC release to a single hit each (three total), but reverted to the previous behavior for the Dreamcast release.
- Spread Shot: A common powerup temporarily upgrades the Shooter's laser to fire a spread of three shots at a time, each offset about 30 degrees. Slightly later, a powerup starts appearing that shoots three shots offset at 90 degrees, and in the end game, an enhanced version of the 30-degree spread shot becomes available.
- Unlikely Hero: As pointed out in the first level's opening cutscene, Wally isn't "one of the usual heroes, in fact, he [isn't] a hero at all". Despite being a simple bean counter, though, he manages to defeat the bug menace and make the world safe for the next hundred years.
- Vicious Cycle: Every hundred years, the bug swarms emerge and the Centipede awakens. Played for Laughs in the ending, when the narrator says "you should see what happens every thousand years".Every hundred years, they try to overtake our world, and we always think we've destroyed them. The legend also has it that every hundred years... we're wrong.
- Video Game Cruelty Punishment: Shooting Wee people causes poisonous mushrooms to sprout where they die.