Ill try and condense the forum design points so far:
01 Looks: Overworld (I believe its officially "Mascot Kingdom') is old and needs to be brought up to date.
02 Necessity: Lots of people like the overworld but its not for everyone. A menu only option would be nice.
03 Fun: Just driving around on it should be an enjoyable sandbox environment to explore
04 Learning: It should contain elements to learn driving. eg environmental hazards, speed boosters, large jumps, shortcuts etc
05 Future proof: Ability to extend game without relying on overworld change.
06 Dynamic: The overworld evolves or unlocks as the player progresses, possibly islands, elevated high-walks, or small walled sections connected with with bridges/gates/doors. Evidence of Nolok also changes with progression.
07 Challenges: Easter egg challenge, hide and seek, etc
08 Interaction: Add some players/karts animated in the world
09 Integration: Add entrances to ther modes like Battle and soccer mode
My additions
10 Appeal: Make it pretty to look at and explore.
11 Scale: make sure all elements look like they exist in the same world
12 Restrictions; No invisible walls or holes to fall through. Model clever limits without making the driver feel it.
13 World building: Overworld is supposed to be "Mascot Kingdom". Their homes or personalities should be apparent.
14 Challenges: Add a giant ball that can just be booted about for fun. Allow secret targets to be hit for achievements.
15 Challenges: Add achievements for 'Air Time', 'Drift Time'
16 Challenges: Add a target practice range for each powerup testing. You drive to a glowing spot that has a constantly refreshing powerup. (eg A bowling alley that resets. or a giant target for the cupcakes)
17 World building: add Achievements scoreboard to tux's garage. This hints at things to do in the world but does not detail how its done.
18 Interaction: A game of tag can be initiated by two or more players holding still for 10 seconds on the "TAG" mat. The mat is only big enough to support 8 players (or whatever our multiplayer servers can support) The game ends when everyone has left. Your percentage of "not it" appears on your chievements scoreboard, along with the name of the global highest scoring "not it" player.
19 User retention: Create a list of daily or weekly challenges on the map using Landmarks so new tracks are not needed to be created for each one.
20 Portability: Try and keep this playable on mobile and lower spec machines (is there a lower limit for this?)
21 World building: Add multiple racetrack paths to the layout. Treat mascot Kingdom like a level in some respects. challenges could be added in future.
22 World building: Add clear landmarks and compass point elements to the map. challenges could be added in future (Like burnout paradise) Eg. "Race from Tux's garage to Nolok's Gate, then to the eastern point, and finish at the top of the mountain". This allows multiple configurable races and challenges using the same map.
23 Future proofing: Leave clear models and development notes for people to tinker with and access. Encourage the open source nature by making it easy to understand and reuse and reskin.
24 User retention: Add some billboards to allow in game promotion of addons or challenges or stk notifications. Yes there is the ticker on the main menu
Make it pretty, make it fun... and you can’t please everyone.