Sky/weather options: Clear, Partly cloudy, Cloudy, Overcast, Hazy, Rainy, Thunderstorm, Blizzard, Foggy, Space, Apocalypse (reddish orange sky)
Terrain: Grassy, Dying grass, Desert, Rocky, Snowy, Flood, Swamp, Forest
Structure types: Stock (blank objects, minimal texture, can change color), Rural (Overlook, Powerhouse), Mombasa (outskirts, turf, metropolis, etc), Jungle (Ghost Town, Sierra 117), Alexandria (exodus, new alexandria), Industrial (The Storm, Foundry, Tip of the Spear), Militia (Countdown, Pillar of Autumn (CE), Space (Orbital, Anchor 9), Covenant (s/e), Forerunner 1 (standard forerunner look), Forerunner 2 (Sanctuary, Delta Halo), Forerunner 3 (Sandtrap, Sandbox), Forerunner 4 (classic, plain forerunner look from the first two games), Flood (s/e), Natural 1 (objects made of snow and ice), Natural 2 (ordinary beige rocks), Natural 3 (whatever).
All I can really come up with for now.
Sandbox was awesome, because you could build a lot of things on it, good enviroment and good feeling. There was no limits, except for the items… -_-