undo for puzzles

andras · Post by **andras** » Thu Aug 19, 2004 5:43 pm

Hi ALL,

I was wondering if it would be possible to add (multiple) undo-s to puzzle type of games?

Long levels could have "save" panels, so that you don't have to redo the whole level when you make a small mistake after 5 minutes of playing.

Thanks,
Andras

Yoshi348 · Post by **Yoshi348** » Thu Aug 19, 2004 5:47 pm

Actually, the game already has a save and load function (defaults to F1 and F2), if that's what you're talking about. The tape playback system is kind of confusing at first, but it also lets you play the game up to just before you died; just click the play button three times.

Guest · Post by **Guest** » Thu Aug 19, 2004 9:19 pm

I did not know about these features.
Thanks for the quick reply.

Andras

Guest · Post by **Guest** » Sun Sep 12, 2004 7:18 pm

Hi Again,

I've used the F1 and F2 for a while, but it is not really convenient for logical games. Pressing "u" for stepping back in the game would be much nicer.

Andras

Post by **Holger** » Sun Sep 12, 2004 11:03 pm

> I've used the F1 and F2 for a while, but it is not really convenient for logical games. Pressing
> "u" for stepping back in the game would be much nicer.

Yes, a step-wise "undo" for logical levels would indeed be a really cool thing. Unfortunately, a real "undo" is not possible with the current game engine, because two different game states and player actions can result in the exact same game state, so it's not possible to "undo" the last step without additional undo information. Unfortunately, this would currently require a huge amount of additional data that would have to be stored, so it's not a feature that I could promise for the near future... But this seems to be practically solvable, as can be seen with the game Sapphire Yours and the tapes which can be played backwards there.

Flumminator · Post by **Flumminator** » Mon Sep 13, 2004 10:40 am

Holger wrote: Unfortunately, this would currently require a huge amount of additional data that would have to be stored, so it's not a feature that I could promise for the near future...

here's an idea that works like a double-buffer:

Have 2 instances of the game-state (that's the huge amount you were talkin of, I think). every time there's a player-input (i.e. an unpressed/pressed-transition on the keys except the snap-modifier) generate the next-frame state into the other buffer and switch over to that. And the Undo-Key would be switching back to the save-buffer.

That's would also mean some work with the current code-base, but should be a lot simpler than implementing reversible tapes.

bojster · Post by **bojster** » Mon Sep 13, 2004 3:01 pm

Still, that would only make one undo step available, not always enough in puzzles... let's say you forget to release arrow button while pushing a bulb and the player goes two steps too far...?

Flumminator · Post by **Flumminator** » Mon Sep 13, 2004 3:13 pm

Well, original Sokoban had only 1 step undo, too, and people had to live with it. And it would be infinitely as much undo as now

If one however would want to have reversible tapes, these wouldn't just have to record when the player does something, but also all object-changes (including direction changes of moving/falling objects).

This would make tapes seriously bigger than now, and I really won't estimate the work for (a) modifing the engine to record these events (b) extending the engine for reverse-play.

I suppose Holger will be quite busy with the compatibility-engines for a long time, so unless someone else does it we'll have to wait for this quite a bit.

Martijn · Post by **Martijn** » Mon Sep 13, 2004 4:41 pm

I think 1 undo is sufficient and not 10 or so. Because the levels get too easy otherwise.