Want to get creative rather than the constant shooting of people in the head. Then you’ll be well happy to hear about the Halo 4 Forge Mode.
For the less initiated, The Forge mode is a build your own level thing so you can create the most dastardly snipe points you can possible imagine.
The video is just a work in progress but does look rather good. there are some new bits and bobs added from previous versions including grabbing tool, respawn tweaks, and a handy duplicating items tool.