This bug has ruined by resuming playthrough Ace Mine 2 levelset from the Emerald Mine Club section; it has ruined 5 recorded tapes, Level 29 through 33. I just found this when I checked the tapes every now and again to make sure they were solvable (and I wanted to watch how I did after a long break from playing Rocks'n'Diamonds - more particularly, playing Emerald Mine-engine style levels).
- It all started when I started using the alternative key bindings for snap and action buttons, or more particularly, Player 2 keybindings. Hmm, I thought: "Did Holger just made it easy for me to use multiple keystrokes for the same actions?" I know for a fact that there are a few games that do that, multiple rebindable keys. However, digging up the older posts, it's a feature.
- It wasn't until I watched the tapes with this effect, with
Player 2 appearing and completely hindering my movement input; it was where it broke the tapes and rendered my proof of solving the levels null.


- The funny (and irritating) thing is that team-mode wasn't enabled in the Setup section.
- The bug is reproducible not only in the Emerald Mine engine, but also in R'n'D engine (and I assume other engines).
- In the level editor, put all the four players (
) in just one empty level, and have an
Open Exit.
- When playing the level in single-player mode, only
should only appear. Control the first player with only
's control keys; go to
.
- Watch the tape of
going into
; it should be recorded the way you intended.
- Replay the level again, this time, by using the other three players' control keys (only snap, and action key, not movement for the moment), and go to the exit.
- Watching the the new tape, you can see that suddenly one of the three other players appeared! Those players didn't appear when you just played the level by yourself in single player! This occurs if you press even one key of one of the three players. If
's control keys is pressed during the attempted recording,
will appear when it saved in tape. This also applies to
and
. Thus, as a result, the other three players' sudden appearance taints the tape. Their appearance prevents the player from completing the level via the tape.
- Retry the level again, this time by using the other three players' movement control keys, and enter the exit once more.
- This is where things get weird:
and one of the other three players move at the same time. If you use
's control keys to move down, both
and
move down together. This also applies to
and
.
- It gets even weirder! When
exits the level, the other three players disappear!
Note that, regarding this ugly bug, it is possible that I haven't explored other possibilities yet (in spite of writing up detailed instructions of reproducing bugs), what if Player 1 isn't in the level alongside Player 2, 3 and 4? Why not mix and match?