S	M	T	W	T	F	S
	1	2	3	4
5	6	7	8	9	10	11
12	13	14	15	16	17	18
19	20	21	22	23	24	25
26	27	28	29	30	31

S	M	T	W	T	F	S
	1
2	3	4	5	6	7	8
9	10	11	12	13	14	15
16	17	18	19	20	21	22
23	24	25	26	27	28	29
30

S	M	T	W	T	F	S
	1	2	3	4	5	6
7	8	9	10	11	12	13
14	15	16	17	18	19	20
21	22	23	24	25	26	27
28	29	30	31

S	M	T	W	T	F	S
	1	2	3
4	5	6	7	8	9	10
11	12	13	14	15	16	17
18	19	20	21	22	23	24
25	26	27	28	29	30

S	M	T	W	T	F	S
	1
2	3	4	5	6	7	8
9	10	11	12	13	14	15
16	17	18	19	20	21	22
23	24	25	26	27	28	29
30	31

Timeline

Alpha Dome v1.1

Nice combo of open and closed spaces. Symmetrical layout with different features in each section (which makes for some disorientation). Textures are used well for differentiation, but these become useless if you find the night vision powerup.

Chris's Cross

Nice concept-a bunch of interconnected small rooms, with a passageway that goes over the top and provides lots of sniper positions. The phfor textures make it a little hard to see any distance at low resolution, though.

Ender

One big (very big) pit, with some sniper positions, and a couple of pathways through some lava. Watch the juggernaut. Comes with a (required) physics model.