MM ScummVM FAQ

Maniac Mansion ScummVM differences

[I have no attention span, Matt, get to it] ScummVM runs of Maniac Mansion are like comparing Wind Waker HD runs to Wind Waker SD runs. They are different games.

Still here, but don't care that much?

tl;dr -- ScummVM is an inaccurate emulator; so much so that you cannot run Maniac Mansion within it and compare your times to my runs. I've done runs on both my original PC hardware (lowly 286 with an official IBM CGA card) and within DOSBox. They are functionally identical. SVM is implements the game so poorly that you'll have to put your SVM runs into a different category.



Wow, you really do care. I love you. Here are the details:


Glossary:
SVM = ScummVM

DOS = Original DOS version, which uses MANIAC.EXE as the interpreter. By this, we also mean DOSBox

Walkbox = You don't control your characters directly in Maniac Mansion. Instead, you click on a destination, and
your character will walk to that destination. In order for the character to avoid objects that are in their way
to that destination, the designers built in invisible lines to guide the characters. These invisible lines are
called Walkboxes. Walkboxes can (and are) connected to one another; imagine a line that branches off like a tree
into other directions. We call these connecting points "nodes". These nodes are very poorly implemented within SVM.

Edna Kitchen Skip = You walk towards Edna, then immediately run away from her in the opposite direction. If you make it to that kitchen door (to the foyer), she'll disappear and you'll be safe. Normally you are supposed to not be able to escape her, and you'll end up in the dungeon. SVM's poor implantation of walkboxes makes this skip absurdly difficult, whereas in the DOS version you have to try very hard to fail.

Green Tentacle Skip = As you approach GT on the second landing, you switch to a New Kid, then switch back. He's frozen, and you can walk by him. Again, SVM botched this very badly. Skipping him by selecting New Kid is possible, but it isn't consistent. On top of that, when you make it past him and are at the top of the staircase, you need to switch to a New Kid *again*, or you'll get knocked back down to GT. In addition, the proper DOS version does not signal GT as soon as you enter the room; instead, only when you scroll a bit to the left. You can also see how the SVM devs decided to incorrectly model the PC speaker. Why they have is still a mystery to me.

1. Walkboxes
      These are implemented poorly by SVM. Well, *very* poorly. You'll see major stutter stepping. Worse, the
      characters do not turn around as quickly when you are locked in to a walkbox. This is most noticeable with
      the Edna Kitchen skip. In the DOS version, you'll turn on a dime. In this one, it takes nearly 1 full second
      for your character to turn around. It can kill runs in a snap. Even worse, the kids will sometimes choose
      an incorrect branch of the walkbox line and end up in an incorrect location. You can see this with NPCs, too.

      It appears that when a character hits a walkbox node within the SVM version, they stop for a second, and
      then continue on their path. This does not happen in the DOS version.

      You can also see that SVM isn't smart enough to override destinations. You can witness this with on
      the front porch. Start off of the porch, near the doormat. Click on the doormat, but then immediately
      click on the bushes to the left. Your character will first walk to the doormat, and then to the bushes.
      This is not true in the DOS version. That version is smart enough to override the doormat destination.

2. The Green Tentacle Skip
      This is a nightmare in the ScummVM version. In both the regular version and the NES version, you are able to
      go to that room, switch to a new kid, switch back, and walk on by a frozen GT. In the ScummVM version, two
      incorrect things happen. First, GT will be activated as *soon* as you enter the room off of the stairs, and
      second, you have to switch to a new kid an additional time once you reach the top of the next set of stairs.
      This adds a tiny bit of time.

3. Script Timing
      Scripts often fire too quickly. Note that I've run the real version on something as lowly as an 8088 and as
      high as a quad core pc, and the scripts will fire at the correct intervals. This is true of the DOSBox
      version as well. In the ScummVM version, Ed will make it back upstairs more quickly. The first real cutscene,
      the "You'll be getting your pretty little brains sucked out" scene, happens about 3 seconds earlier in the
      ScummVM version. It is supposed to go off about 1 irl minute after you use the key in the front door. In
      SVM, it *does* set the timer when you use the key in the front door, but the ScummVM internal timer is
      not correct, so the script fires too quickly.

4. No Lag Where There Is *Always* Lag
      This is the worst offender. Again, I've run Maniac Mansion on a 286, and the Garage Door opens slightly more
      slowly than on a 486. However, even when I ran this on a quad core pc running pure DOS, the garage door will
      still lag the game like crazy. It is not because of the game having to draw such a huge graphic; no, it is
      because the garage door is actually *multiple* smaller doors stacked upon each other. It is possible, through
      the in-game "*ch4mysocks" debug code to open up only tiny bits of the door, haha. Anyway, the game is lagging
      because (most logically) the interpreter is acting up multiple objects all at once. Since SVM is a brand new
      interpreter,  it doesn't have the same issue of the multiple object lags. And again, no matter how fast your
      PC is, the "real" version of the game will lag there. I've booted DOS up on my quad core blazing fast
      machine and that door lags there.

5. Sound Effects
      Haha. You get the option for PC Speaker emulation, but SVM still plays incorrect SFX.

6. Cursor Movement
      This is an odd change, too. The cursor in the real version moves in 8-pixel increments. Withing SVM,
      they have it move at 1-pixel increments. On top of that, the motion speed of the cursor is laser sharp
      within SVM, but there is pretty much 0 acceleration within the regular version. This means you'll be able
      to click on objects much more quickly and much more accurately within ScummVM. This can give you a slight
      edge with timing.

7. Screen Transition Fades
      Now, again, the screen transitions are one issue. Granted, my screen transition is a bit slower if I'm using
      a CGA card on a 286 (which I did). Still, there's a negligible difference in timing with that and DOS or
      a faster PC. In SVM, the fade in/out to go from room to room/scene to scene is very very fast. This does
      have an impact on the overall time.

8. Steel Security Door
      Even if you have legally purchased your version of Maniac Mansion (the version I use is from the original 5.25" disks from 1990), SVM will hack the game. The Steel Security Door is always open in this version. This would be like firing up SNES9X and seeing that the devs removed the opening credit sequence from Super Mario World.


And those are just the obvious audiovisual errors. We can get even deeper with the difference between the copy protected version of MM (which requires a whole new set of tactics, due to the way the Inner Lab Door is coded) and the version that everyone runs right now (including me).

That said, I can't find a compelling argument to use SVM. DOSBox is easy to use, and it is accurate to the point that you cannot illustrate any differences between my CGA run on my 286 and my run within DOSBox. If someone demands proof, I'll run DOSBox within CGA mode, put up the video of my 286 run, and reproduce it exactly.

Until then, in my mind, this case is closed. If you choose to use SVM, you'll need to create an entirely new WR category for it. My 5:58 WR still stands until someone can beat it within DOSBox (caveat: you cannot use a turbo mode, which should be obvious, but the temptation to cheat is always there) or on an original piece of hardware running native DOS.