-=== NEED - Skills ===-
Walker
Stoner
Platformer
Builder
Stacker
Cloner

-=== NEED - Objects ===-
One-way force fields
Pick-up skills (single and multiple-in-one)
Teleporters
Buttons and locked exits
Splat pads
Splitters

-=== NEED - Other ===-
Highlighting a lemming
Zombies
Fall height ruler
Talismans
Fine control reminder?


-=== DONE - Skills ===-
Climber
Swimmer
Floater
Disarmer
Bomber
Blocker
Basher
Fencer
Miner
Digger

-=== DONE - Objects ===-
Entrance
Exit
Water
Fire
Traps
Updrafts

-=== DONE - Other ===-
Fine control
Scrolling
One-way arrows
Time limits
The deadly edges and ceiling
Release rate manipulation and locked release rates
Clear physics mode