Chip's Challenge - Lynx Mode

Unplayable Levels

This section describes those MS-specific tiles, tile combinations and features that just won't work in Lynx, and can make a level completely unplayable.

Invalid tile combinations

The principles to determine what tile combinations are valid in Lynx are very simple.

• Monsters, blocks and Chip are moving objects.
• All other types of tiles are static objects. Even objects that can be picked up (boots, keys, chips) or removed (bombs, doors, sockets) fall into this category.
• A tile can have only one static object, with optionally one moving object on top of it.

It's as simple as that. The only other restriction is that there must be exactly one Chip on the map.

But the MS levelset file format allows two layers of tiles, and any type of tile can be placed on either layer. It also allows multiple Chips (the last one is used) or no Chip at all (Chip appears at the top-left of the map). If any such invalid tiles are found in the map when playing in Lynx mode, Tile World will say that "This level cannot be played".

Ignored tiles and features

There are some other MS-specific features that were not present in Lynx. Though these will not render the level unplayable in Tile World, their resulting behaviour and appearance in Lynx mode will not be what was expected. Furthermore, some of these behave differently in Tile World 1.2 and Tile World 1.3.

Following is a list of such features:-

• Monsters marked as stationary / non-moving in MS will be normal monsters - i.e. they will move - in Lynx. Similarly, clone blocks that are not placed on top of a clone machine will be normal movable blocks in Lynx. To achieve the same effect as in MS in Lynx, an unconnected trap can be placed below the object.
• In MS, a "regular" block on top of a clone machine creates a machine that is activated simply by pushing at it. In Lynx, this creates a normal button-activated machine that clones north.
• The tiles corresponding to intermediate graphics in the game, viz., water splash / drowned Chip, burnt Chip, bombed Chip, explosion, disintegration, exited Chip, fake exits, swimming Chip and a couple of "unused" tiles (one is an 'overlay buffer', and the other is now used as the ice block in some patched versions of MSCC and TW) - will not give the same effect in Lynx.
  • Swimming Chip will not be killed by monsters as in MS, and is replaced by a wall in TW 1.2.
  • Fake exits either become walls in TW 1.3 or real exits in TW 1.2. Either way - not the effect that was intended.
  • The other tiles (except exited Chip) will become walls (either real or invisible ones) - which is functionally the same as MS, but visually much easier for the player to identify, e.g. in a maze.
  • Exited Chip is the only tile that seems to behave the same in MSCC, TW 1.2 and TW 1.3.0. But even this might change in a later version of TW, since the expected behaviour in Lynx is pretty much undefined.
• Invalid trap and clone machine connections will be discarded, and won't do any of the funky things that MSCC does.

Finding what makes a level unplayable

If you're a level designer who has created levels without Lynx compatibility in mind, and you now want to find out whether any of your levels are unplayable in Lynx and what makes them so, here's what you can do.

Using Tile World

1. Open your levelset in Tile World's Lynx mode, with passwords disabled.
2. Step through your levels one by one by pressing Ctrl+N. Stop when you reach a level where Tile World says "This level cannot be played.".
3. Check the errors that Tile World reports to the stderr device. On Windows this is the file stderr.txt in the Tile World directory. Here are some sample errors:-
   Level 133: multiple Chips on the map! [lxlogic.c:1873]
   Level 135: Invalid "buried" tile at (30 21) [lxlogic.c:1851]
   
4. Open the level in an editor and check the tiles at those co-ordinates.

Using Chip's Workshop and a special tileset

1. Download and install Chip's Workshop.
2. Download the tileworld-48x48-compat.zip tileset. Extract its contents to ChipW's tilesets folder.
3. Start Chip's Workshop and open your levelset.
4. Go to "View → Select tileset..." and select tileworld-48x48-compat.tis.
5. Now, most invalid tile combinations and some ignored tiles will be marked with a red cross. Here are some examples:-
   
   Problems that won't be highlighted by this tileset are: moving objects on top of other moving objects, clone blocks not on a clone machine, a normal block on a clone machine, stationary monsters and multiple/missing Chips.

Avoiding creating unplayable levels

If you're a designer who's creating new levels or updating existing ones, and would like the editor to help you avoid invalid or ignored tile combinations, you can use either Chip's Workshop or ChipEdit, which have some features to do that. The other editors available as of this writing - CCEdit and CC Level Designer - are not known to have any such features.

In Chip's Workshop

When you want to place objects on both layers of a tile, just use Shift+click. If the tile you're placing is a moving object it will go on top. If it's a static object, it will go below any moving object that's there, or will become the only object. The Tiles pane doesn't include the ignored tiles, so you won't be tempted to use them.

In ChipEdit

Ensure that you have "Options → Check" enabled. With this set, ChipEdit will not allow you to place invalid tile combinations on the map or let you use the ignored tiles. If "Options → Show Errors" is also enabled, then an error message will pop up when this happens. Note that ChipEdit says that walls, invisible walls, popup walls, doors and sockets can't be buried, though it's valid to place these under moving objects; and it also considers ice-on-ice to be valid, though it isn't.

Well, that was all about making a level playable in Lynx. Making a level solvable - in the same way in both rulesets - requires some understanding of the differences in behaviour... Up next.