Mr. Driller Ace: Strange Bacteria, often shortened to Mr. Driller A or referred to as Mr. Driller Ace: The Wonderful Pacteria is the fourth game in the Mr. Driller series and the first to be released exclusively for consoles. It would also be the first game to use the larger character models that would later go on to be featured in Mr. Driller: Drill Land and Mr. Driller Drill Spirits.
- Susumu Hori (uses special knight's armor in Wonderful Pacteria mode)
- Anna Hottenmeyer
- Ataru Hori
- Taizo Hori
- Usagi (secret character)
Wonderful Pacteria's gameplay is heavily based on Scenario Driller from Mr. Driller G, in that it is played with Dristones. It can only be played as Susumu Hori, who is dressed in special knight's armor with a sword instead of his usual attire.
As with Scenario Driller, "drilling" one block will deplete 1% from the player's air gauge, while getting squashed will drain 20%. As the player descends, buildings will appear, which can contain a residential Undergrounder, a Shop, a "Travel" station that will allow the player to leave the stage early, and a hostile monster such as a Pooka or Fygar that will attack the player and drain their Air.
Mission Driller returns as the "standard" driller mode, with the same six characters from G plus Usagi if he is unlocked being playable.
- Japan (500m, 5 floors)
- France (800m, 8 Floors)
- Amazon (1500m, 15 floors)
- Space (Endless, uses items)
A sequence of stages in a GP is played, with the player racing holograms of the other five Drillers the player did not select.