Alright, so I have some great ideas for Halo 5, here ya go
------[ Forge ]------
[] Customizable land and sky color
-Now I thought this would be cool, so lets say your on a grassy map. You can go into "Customize" in the menu and choose land color, vegetation color, sky color, and water color.
[] Wield tool
-This is probably the best, you can wield objects to vehicles and save that vehicle.
[] Vehicle settings
-In vehicle settings you can change the color, speed, and weight.
[] Security cameras
-And can link with monitors. You can make it so players have to manually sync it on the map or it is automatically.
[] World Size
-You have a HUGE map to build on, but by entering each one you have so select and arena to load.
-By clicking "World size" in a menu, it shows a top down view of the map with a square over the area you can build in and you can drag that square any where you want, and it will load that section.
[] Trees and plants!
-I've always wanted to place vegetation in my maps
[] Particle effects
-You can place fog, smoke, fire, and blood.
-But you have a limited amount
[] Openable doors
Last but not least...
---[ ADVENTURE ]---
In Halo 5, there should be a new game type called "Adventure" were you set the goal of the map so it could be like "Cross the finnish line" or "Escape from building" or kill all the covenant.
In adventure you can place NPC's like grunts, elites, jackals, BRUTES, Hunters, and skirmishers.
Also you can place objectives and missions by talking with marines around the map.
**You can also make cut scenes with theater mode, and place in a timeline of events!
Hope you liked my ideas, hope you consider them.
