Nova the Squirrel 2 level format

.---------------------------------------
| Level header
'---------------------------------------

0        1        2        3
DMMMMMMM XXXXXXXX VvLI.... ...YYYYY
D = If 1, player starts facing left
M = Background music
X = Starting X position (or Y position, for vertical levels)
v = Enable vertical scrolling (or horizontal scrolling, for vertical levels)
V = Vertical level
L = Layer 2 level
I = Layer 2 interaction
Y = Starting Y position (or X position, for vertical levels)
Room for more flags

4        5
gggrrrrr .bbbbbgg
RGB Level background color

6       7
BBBBBBBB ........
B = Background ID (or 255 for no background)
Room for more flags

8        9        10       11
llllllll LLLLLLLL ssssssss SSSSSSSS
l = Low byte of level data pointer
L = High byte of level data pointer
s = Low byte of sprite list pointer
S = High byte of sprite list pointer

12       13
abcdefgh ijklmno.
Insert vertical scroll barriers between screens:
Bits:     a b c d e f g h i j k l m n o
Screens: 0|1|2|3|4|5|6|7|8|9|A|B|C|D|E|F

14 15 16 17 18 19 20 21
Eight 8-bit sprite graphic slot values

22+
gggggggg GGGGGGGG
gG = 16-bit graphical asset list, could be a palette, tiles, or whatever

??
11111111 11111111
End of graphic asset list

.---------------------------------------
| Background settings
'---------------------------------------
0        1
TWvvvhhh ........
T = If 1, background is two screens tall
W = If 1, background is two screens wide
v = Vertical speed of background (index into same, but also controls )
h = Horizontal speed of background (index into 1:1, 1:2, 1:4, 1:8, 1:16, 1:32 or 1:64)
Room for some more flags

After this is a compressed tilemap. Tileset is listed in the per-level tileset.

.---------------------------------------
| Level data
'---------------------------------------
Level data:
TTTTTTTY YYYYXXXX [SSSSSSSS]
T - Object type (0-111)
Y - Y position absolute (0-31)
X - X position relative (0-15)
S - Settings byte, if needed
    (may be more than one byte)

.---------------------------------------
| Level data (commands)
'---------------------------------------
Level commands
1111TTTT [SSSSSSSS]
T - 0 level is over, stop processing
    1 set X to S
    2 write 1 column byte at current column
    3 write 2 column bytes starting at this column
    4 write 3 column bytes starting at this column
    5 current X -= 16
    6 current X += 16
    7 special command (S selects which one, and additional parameters are taken)
    8-F: Reserved

Special commands:
(Numbers not assigned)
Switch to filling in the alternate level
Layer 3 effects
Per-level assembly routine

.---------------------------------------
| Sprite/actor data
'---------------------------------------
XXXXXXXX D..YYYYY tttttttt abcdTTTT
tT - Sprite number (T is higher bits)
D - direction (1 is left)
abcd - misc sprite information
X - X position (0-255) (or Y position for vertical levels)
Y - Y position (0-31)  (or X position for vertical levels)
List ends in $ff (so you can't put anything on the rightmost column)