Game Resources / DOS / Jazz Jackrabbit

Speeds of motion:

Motion	Pixels per frame (no speed bonus)	Pixels per frame (speed bonus)
Normal running	6	12
Running uphill	5	12
Hurting horizontal	4	4
Jumping/falling vertical	6	12
Hoverboard max horizontal	6	(unknown)
Hoverboard max vertical	3	(unknown)
Pipe horizontal	10	(unknown)
Pipe up	6	12?
Pipe up from springboard	13	13?
Pipe down	(falling speed)	(falling speed)

Note that many bumps and height changes in upward direction (even slight!) count as upslope (especially end of those sagging bridges).

Note that also glancing blows to edges slow Jazz down to 5 pixels (unknown with speed bonus) per frame.

If you get yourself into a wall, you will get stuck, so no zipping.

Controls:

Controls are normally polled every second frame. Sometimes this frame changes between odd and even (what happens on exact change is unknown), which makes hex-editing real pain. This makes controls bit clumsy for TAS.

Firing every second frame

Even if it would seem that maximum fire rate is ~15Hz (1/4 of 59.7Hz VGA Vrefresh), it is actually ~30Hz. This is accomplished by simply pressing and releasing fire button (space) on alternate frames. Note that in some cases input phase changes mid-firing, in these cases button must be held/released for two frames to fire at fastest possible rate.

Pipe specials:

Upward pipe speed is normally 6 pixels per frame, but if jumping into one, it will take whatever velocity Jazz had when starting the jump (thus, if you enter using springboard, it will be 13 pixels per frame).
Upward pipes "suck" Jazz only after he has stopped ascending.
Some downward pipes hold Jazz up (only falling 2 pixels every second frame. Holding down speeds this process a bit (saving maybe 2 frames).

Simultaneously on ground and in air

This is to be avoided. By hitting border between level ground and downslope, game can get confused and not let you jump. One place this can happen is after the first drop to wide hole in Diamondus level 1 (the first level of episode 1).

Short springboard jump

In contrast to previous, this may be useful. If Jazz takes "standing still" pose during springboard jump, the jump will be bit short. Useful in Tubelectric 2 to avoid hitting the electric eyes enemy on top of blue springboard jump (also useful if height of jump is limiting factor in speed).

Shooting the exit sign

Jazz should be as close to exit sign as possible when it gets shot. The reason is that exit sign will be scrolled to center of screen before score countdown starts, and this scrolling is slow. The time difference this makes can be half a second.

This is also applicable to episode bosses (they too will scroll something to center of the screen after they finish blowing up (and one presumably needs to have further input).

Score countdown cancel

When score countdown has lasted long enough (when counting down from 300, the score is about 27 at this point), firing weapon will cancel the countdown. Saves about 1.5 seconds per countdown.

Getting damage-knocked forward

If you turn just before getting hit, you will get knocked forward. The damage knockback speed is 4 and acceleration will resume from that value.

Relative to full running speed, taking damage is 9-10 frame loss if Jazz has no speed bonus, and 18-19 frame loss with speed bonus.

Taking damage is really to be avoided if at all possible if something blocks the arc Jazz flies when taking damage (because the speed will be zeroed) or if taking damage will cause bigger fall (just the time loss).

RF missile damage

RF missile launcher shoots two missiles at once. If both hit, it will do more damage than blaster or toaster (enough to kill normal enemies on turbo difficulty). Useful to kill some enemies in tight spaces when there's no time for double shot.

Also, RF missiles fire bit upwards and downwards, which is sometimes handy for taking out some enemies (like those electric eye enemies in Tubelectric level 2 (fourth level of 1st episode.

TNT exit trick

In some levels (like Holidaus 2 in Holiday Hare '94), it might be possible to get fairly close to exit sign with some parts of level still remaining. If one uses TNT ammo there, it might be possible to hit the exit sign, triggering the level end sequence (the scroll will be long however).

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