Well-Formed

How to play

The rules are XML's, taken literally

The snake is the document you are writing. Its tail is the root element, every segment after it is an element you opened, in document order, and the lit ones are the elements still open — the stack a parser keeps while it reads.

1. <title><item>

   1Open tags to grow

   Eat a start tag and that element opens inside the one you are in. Every element you write adds a segment, and the deeper it is, the more it scores.

2. </item>

   2Close the innermost

   Every open element's end tag is somewhere on the board, but only one is safe: the innermost's. It pulses, in the colour of its segment.

3. </channel></guid>

   3Anything else breaks it

   Any other end tag is a mismatch. So is running off the board with elements still open, or into your own document.

4. </rss>

   4Finish the document

   Write the level's quota of elements, close everything inside, and the root's end tag finishes the file. The next level is a different format, and faster.

Arrow keys or WASD steer, Space pauses and M mutes. On a phone, swipe on the board or use the pad beneath it.

Scoring

Dive deep, then unwind in one go

Depth multiplies everything, and end tags eaten back to back chain into a combo. Five elements deep and closed in a single run is worth several times the same five closed one at a time — and a snake five elements longer, with four traps on the board.

Start tag

10 × depth40 at depth 4

End tag

25 × depth × combo300 at depth 4, third in a row

Finished document

50 × elements + 250 × level1,350 for 12 elements on level 3

A finished run can go on the global leaderboard: today's daily challenge, where everyone was dealt the same board, or all time. It goes under a name the game deals you, such as <brisk-element-42/>, and it is not taken on trust. The server replays every move from the seed it dealt, and only the score the replay reaches goes on the board.