Mechanic · structure & scoring · fixed shooter

Bonus stage

A stage set apart from a game's ordinary stages for a distinct challenge.

stubAlso: bonus stages, challenge stage, challenging stageUpdated 2026-10-22
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  2. Games
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  4. Sources

A bonus stage sets a stage apart from the ordinary sequence for a distinct challenge. Galaga marks every fourth stage as a challenging stage1.

  • ScheduledGalaga (1981). Every fourth stage is a challenging stage.1

Games

GameYearHowNote
Sonic the Hedgehog1991enough rings at an Act's end open a rotating maze with a Chaos Emerald
Sonic the Hedgehog 21992a checkpoint post touched with 50 rings opens a race down a chute for a Chaos Emerald
Galaga1981Scheduledevery fourth stage is a challenging stage
Super Mario Bros. 21988Slot machinea slot machine after each level, one coin a spin
Every claim about this mechanic, by game (3)
Galaga 1981Every fourth stage of Galaga is a challenging stage: at each stage's start stg_init_splash adds 1 to the stage counter and stores (counter + 1) mod 4, and a 0 there marks a challenge, so the counter values 3, 7, 11, … bring one.Code
Super Mario Bros. 2 1988The Bonus Chance after a level spins three reels of eight positions, one coin a spin. Each position holds one of four symbols: a Snifit, a turnip, a star, or a cherry. Each reel steps every 4 frames, and A stops the leftmost still spinning. A cherry on the first reel wins a life, cherries on the first two win two, three cherries five, and three of another symbol one; lives stop at 255. Each reel holds one cherry.Code
Both games end a level with a Bonus Chance, and Doki Doki Panic's disk holds Super Mario Bros. 2's 24 bytes of slot-machine reels with two exceptions. Where SMB2's first reel has a turnip (its second symbol) and a Snifit (its fifth), the disk has $00, the value SMB2's code reads as a cherry, so that reel holds three of SMB2's cherry values on the disk and one in SMB2. A cherry on the first reel wins a life.Code

References

  1. ^ abEvery fourth stage of Galaga is a challenging stage: at each stage's start stg_init_splash adds 1 to the stage counter and stores (counter + 1) mod 4, and a 0 there marks a challenge, so the counter values 3, 7, 11, … bring one.Codeneiderm/arcade
    How we know
    180;; stg_splash_scrn()
⋮
183;;   Increments stage_ctr (and dedicated challenge stage %4 indicator)
⋮
191; plyr_state_active.stage_ctr++
192       ld   hl,#ds_plyr_actv +_b_stgctr           ; ++
193       inc  (hl)
⋮
195; plyr_state_active.not_chllng_stg = *HL & 0x03  ... gives 0 for challenge stage
196       ld   a,(hl)
197       inc  a
198       and  #0x03
199       ld   (ds_plyr_actv +_b_not_chllg_stg),a    ; ==(stg_ctr+1)%4 ...i.e. 0 if challenge stage
    galag/galagao_ASxxx/rom0/task_man.s lines 178–202 at 248be0d · upstream ↗
    1443; challenge stage e.g. 3,8,10 etc. 8 unique challenge stages.
    galag/galagao_ASxxx/rom0/gg1-3.s line 1443 at 248be0d · upstream ↗

    Checked against the evidence by its author, an AI model, 2026-10-21.

    Checked by a second AI model, 2026-10-21.

    In the claim ledger

Sources

Code