Another new puzzle! This one isn't particularly deep or complex

(solving it only requires matrix inversion over GF(2), whereas
several of the other puzzles in this collection are NP-complete in
principle), but it's a fun enough thing to play with and is
non-trivial to do in your head - especially on the hardest preset.

[originally from svn r5967]

list.c

@@ -19,6 +19,7 @@ echo -e '};\n\nconst int gamecount = lenof(gamelist);'
 
 extern const game cube;
 extern const game fifteen;
+extern const game flip;
 extern const game mines;
 extern const game net;
 extern const game netslide;
@@ -32,6 +33,7 @@ extern const game twiddle;
 const game *gamelist[] = {
     &cube,
     &fifteen,
+    &flip,
     &mines,
     &net,
     &netslide,