- Scalable primitive pieces: no more having to replicate a block 500 times just to get a flat wall, simply make it bigger! This implies nicely repeatable patterns/texturing work.
- Invisible Walls: cut off pieces of the map without blocking scenery. Glass Mazes!
- Custom Image Previews for maps in lobby/website.
- All Forge-specific spaces MUST come shipped with the game on disc - no more late releases a la Foundry/Sandbox and Forge Island.
- No in-built invisible walls: Expect people to build outside the usual bounds and let whatever will be, to be.
- Importer for Halo 3/Reach/4 Forge Maps: Imagine 7 years worth of community content available on day 1 - WOW! Also, familiar Forge spaces would allow Forgers to hit the ground running with ideas for maps with new gametypes and maps enabled by new features.
- Proper in-game Forge Tutorial. Forge is still super intimidating to a lot of people. So I think a mode where 343 Guilty Spark actually walked you through the basic controls and object manipulation and guided players through making some toy map concepts would help a lot.
- Virtual Reality object editing. Let me get my hands on those forge pieces and move them around naturally! (also need: Xbox compatible VR headset and neo-VR gloves)
But by far my biggest wish is that just as much effort is put into the gametype engine and customisation thereof. As we saw in Halo 4 compared to Reach, maps are cool and all but changing the rules of play is (more than) half the experience.