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Proto:The Bugs Bunny Birthday Blowout

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This page details one or more prototype versions of The Bugs Bunny Birthday Blowout.

To do:
Compare the unfinished bits of Stage 4 to the final game.

This prototype of The Bugs Bunny Birthday Blowout is a pretty early build. Layouts for the first four worlds have been worked on, though it isn't possible to complete any of the stages at this point.

The ROM image that had been circulating the internet for many years unfortunately had a number of corrupted bytes, which largely affected tilemaps and level layouts. A clean ROM was finally made available in June 2022.

Download.png Download The Bugs Bunny Birthday Blowout (prototype)
File: The_Bugs_Bunny_Birthday_Blowout_(Prototype).zip (96 KB) (info)


Stage 1
The most complete stage, but that's not saying much.
Stage 2
The obligatory desert stage.
Stage 3
The volcanic stage. Watch out for lava!

General Differences

  • There are no copyright, title, or story screens. The game throws the player to Stage 1-1 immediately.
  • All objects, including Bugs, move at about half the speed they do in the final. This also means that the floating platforms have their ranges halved, making some sections impossible to cross.
  • There are no giant carrot objects present, meaning levels cannot be completed. The code for the object is present and partially functional: touching it will cause Bugs to float off the screen in a balloon as in the final version, but the level still doesn't end, and the music loops indefinitely.
  • There is no lives system, so it's not possible to get a Game Over. Code-wise, the basic framework for the system is in place, but it is hard-coded to jump to the same code path regardless of the life counter's value.
  • Carrot icons do not make a sound when collected.
  • Powerup icons do not make a sound or disappear when collected, though they do still set their corresponding flags at $430 in RAM:
    • Speed up (01): This functions as a high jump in the final game.
    • Hammer (02): This would kill more powerful enemies and bosses in one hit, if there were any to actually use it against.
    • Unknown (04): This was replaced with the heart in the final game (see below). There is no code in either the prototype or final game that reads its associated flag, so its intended functionality is unknown.
  • Powerup flags are not reset after taking damage or losing a life.
  • Crumbling rock platforms are marked with different palettes to identify their type (delayed or immediate).
  • Bugs does not dive in and out of tunnels. The tunnels behave much more like the pipes in Super Mario Bros.
  • There are four debugging functions available: hold Start when starting the game to get a stage select menu, B to start on Stage 2-2, or A to go to a preliminary version of the Mole Game. You can also moonjump by pressing Select.
  • The Mole Game is more of a graphical demo than an actual game at this point. The moles cannot be hit, Bugs' sprites are glitched (due to a mismatch between his tilemap and the actual CHR layout), and both the music and the game loop indefinitely. It is possible to "end" the game before it starts (triggering the otherwise unused messages "CARROT IS SHORT" / "SEE YOU AGAIN.") by freezing the carrot counter at 0, though it is programmed to simply restart from the beginning when this happens.
  • All of the music tracks used in the final game are present and complete, though a good number of them are unused at this point in development.

Graphical Differences


For graphics that appear in multiple levels.

Proto Final
Spin me around. Where'd it go?

The disappearing platform in the final was a more complicated spinning platform at this point. The design was simplified to make room for Bugs' diving animation, but while the platform "disappears" it still spins, so if you were ever wondering why those platforms had weird collision...now you know.

Proto Final
Needs improvement. Better.

The graphics of Bugs and the balloon's basket were improved for the final.

Proto Final
What? The universal symbol for health.

The heart was originally a bunny head next to some odd-looking waves in the prototype. This item sets a flag in RAM in both the prototype and final versions, but no code seems to actually read it; it's possible the item originally served a different purpose, and the heart functionality was tacked on later in development.

Proto Final
Who's got the bomb?More bombs than Don Bluth in the 90s. Alarm clocks have been known to explode.It's Explode o'clock.

The alarm clock is a bomb in this build. Same function, though, and the clock makes more sense thematically.

Proto Final
Elmer Fudd is after dolphins now. Nets work better in cartoons than reality.

Elmer's nets were given more detail in the final.

Title Screen

Proto Final
Happy Early Birthday Bugs! Now it looks empty.

Although the prototype normally bypasses the title screen, it is present in the ROM and can be seen by changing ROM address 0x1E752 to $40 and holding A as you power on/reset the game.

At this point, the chains are larger, the letters of the title have some shading that was removed in the final, and there are little squares around the border.

Mole Game

Proto Final
Isn't it cute? Remember him? Of course you don't.

The Mole Game has actual moles in the prototype. The final instead uses Willy the Weasel.

Proto Final
Puffy clouds. Woo.

This change altered the title graphics as well, replacing the unique graphics of the prototype with a rather plain-looking text box in the final.

Level 4

Proto Final
Through thin... ...and thick.

The pipes in this stage are thinner in the prototype.

Level 5

Proto Final
Free-roaming. Caged.

The tileset for Level 5 is seemingly older than the rest, as it does not yet contain any powerup icons, only a single carrot graphic in a completely different style from the final icons. This was likely changed because, being a background object, it could not be placed on anything but an empty sky background without creating a big ugly hole.

Proto Final
Awfully plain. I guess you could say it was trunkated. If you were a jerk.

The inclusion of powerup icons meant that some graphics had to be removed, so the second tile for the tree trunks in the prototype was overwritten in the final. The trunk was also given some additional shading.

Proto Final
Neat. Pink?!

Another victim of tile overwriting: the unique spike graphics were changed to the simpler 8×16 ones used in other levels.

Level 6

Proto Final
It sure is a vase. Exciting stuff.

The lip of the vase was changed slightly in the final.

Proto Final
Your beach ball deflated. "But that's not a football!", you say.

The (American) football was redrawn to look more like a...well, football.


There's no ending in the prototype, but the graphics are there.

Proto Final
Down Syndrome Bugs? He's reading the ending dialogue.

Bugs' eyes were redrawn to remove the cross-eyed look of the prototype.

Proto Final
I surrender! Trying to kill Bugs does not count as a "funny trick", guys.

And again.

Proto Final
That bright shade of blue didn't help either. No rabbit ears, guys.

Road Runner and Pussyfoot were removed from the photo in the final, probably because they don't actually show up anywhere in the game. Taz's oddly-proportioned stomach was fixed in the final.

Unused Graphics

Graphics that are mostly absent from the final.

Mole Game
It's okay.
Various tiles from the Mole Game. Most of these are still present in the final version, with only the normal mole head and the first three letters of "SORRY" having been removed.

Speedy Gonzales
Pulled over by the P.C. police.
Yep, it's him. His sprite only appears in the prototype, though there doesn't seem to be an object associated with these graphics.

Spiked Ball
You know, like in the movies.
Just a simple spiked ball.

These odd tiles take up a character bank in the prototype. It's unknown what they would have been used for, or if they were even intended for this game, though it's possible that the letters were originally intended to be powerup icons before the final icons were implemented as background objects. These were replaced with the Game Over and copyright tiles in the final.

Audio Differences


There's an extra piece of music in the prototype which is used while Bugs walks into frame. Normally, this cuts off after about one second, but the rest can be heard by changing ROM address 0x1950B to $60.


The death jingle is 20% faster in the final.


The World 3 song has a 2.5-second intro which was removed from the final track.


The bonus stage song is about five seconds longer than the final, and has a different ending.



Bugs' hammer sound in the final has a second pulse channel component, which is not the case in the prototype.

(Source: Original TCRF research)