Judge Dredd mode stack bug

I discovered an interesting bug the other day that allows you to stack modes in Judge Dredd. If you collect the first sniper tower hurry up and start multiball while the second hurry up is still running, it the mode will not stop like usual. Instead, the mode will continue to run during multiball. Moreover, the next mode start light will relight during multiball, allowing you to start another mode during multiball. Even more unusual is that you can stack in a second mode as well. You can only get as many as two modes going at the same time. After all modes have finished running, things seem to get back to normal.

Unfortunately, things don’t behave exactly like you’d expect during mode stacks. For example, I tried stacking blackout with regular multiball in the hopes of hitting double jackpots, but for some reason the jackpots will not light during this stack. Stacking bad impersonator with multiball is a mess, because both modes want the center drop target in different states, so the center drop target goes up and down repeatedly. I was able to stack blackout with ultimate challenge (very hard to pull off), but the ultimate challenge jackpots aren’t doubled.

Has anyone else found this bug? Is there a way to exploit it for big points? Right now, it seems like something to be avoided more than anything, but it would be neat if there is some scoring potential in there.


What code version?

Very cool, thanks for posting this!

You mentioned the modes that don’t stack well with this, but I would imagine that most others do…assuming that things like Safe Cracker would allow you to collect mode shots and jackpots simultaneously, and that left ramps would collect mode shots and light jackpot shots?

L6. Apparently there is an L7 available, i wonder if it got patched there?

Pretty sure safe cracker is another that doesn’t play nice. Its odd, on some of the modes you just cannot light a jackpot. Shoot the left ramp over and over and it does nothing. (but the callouts will keep telling you to “shoot the left ramp”)

I got stuck in this bug during a tournament a few months ago. I was playing a long multiball but it wasn’t giving jackpots and kept starting new modes. No one knew how to handle it, so it was ruled catastrophic and we moved on. I figured it was just something wrong with that specific machine, but now I’m more curious about how I got into it and exactly what I had running.

Yeah, as of right now it seems like this bug is more an annoyance than anything because it interferes with your ability to get jackpots.

I think you can also start the bug by hitting a few shots in safe cracker, then starting multiball.

As a rule of thumb, best avoid starting multiball when you have a mode going on JD. At best you lose any points you earned in that mode and will have to start over when you drop out of multiball. At worse, you trigger a bug that will cost you points in multiball.

Edit: confirmed you can trigger the bug by hitting a few shots in safecracker and starting multiball while the mode is still running.