This is just a rough idea I've been spinning through my head, but I was considering  how I'd tackle a particular part.

The main premise is you can construct a variety of vehicles to use in the world, via a series of different parts, in the vain of Space Engineers and Crossout. The focus will be more on 'cool and aesthetic' than totally super realistic, a player would be rewarded for creative design. As such I wanted vehicles to have a variety of propulsion methods such as wheels, tracks, repulsors (hovercraft), hoverjets (VTOL), aerojets (aircraft), etc.  And of course mechanical legs. Realistically legs have numerous issues, and some of these would be unavoidable (legs tend to give you a higher profile for example).

So I hope to get ideas for what would make creating a legged vehicle advantageous and amplify them to make them a valid choice. Maybe if I go over what I consider the advantages/disadvantages of the others.

Wheels: Cheap to produce, vehicles travel reasonably fast, can carry a moderate amount of mass. Easily damaged? Often suffer greater extremes of slow down on difficult terrain.

Tracks: Moderately costly, tough, able to traverse a number of terrain types without great amount of slow down, can carry heavy masses. Slower than the rest.

Repulsors: Ignore most surface terrain, very fast, can cross liquid surfaces. Expensive, trouble going up inclines? Can only carry lighter masses.

Hoverjets: Allow aerial movement, direct vertical movement, fast. Very expensive, can only carry the lightest mass.

Aerojets: Allow aerial movement, fastest vehicle. Very expensive, always in constant motion and requires advanced landing techniques and sufficient flat ground to land, lighter mass.

I think the main advantage of legs is also obstacle traversal, except with even better results. Flat or rough terrain don't make a difference / no penalties.

Also with "gripped" legs you could have full-on climbing capabilities.

Otherwise yes, they're fragile. Depends if you're thinking heavy mech type of legs, or more agile spider type of legs.

Another possible advantage is that the load it can carry shouldn't affect it too much. Think of a robot with 8 legs, moving 2 at a time, while the load rests on the other 6. Only part of movement that would be affected by the load would be moving the body over to the 2 legs that just advanced, which could probably be less than wheeled vehicles, that constantly need to move under the weight.

I think legs definitely will have a terrain movement advantage and be able to traverse steep inclines better than most other vehicles.

The main thought since my post, perhaps not the most realistic, came from where I was deciding on the support of mass of the different types above, I think I'll have legs able to support the heaviest mass with the least amount of movement slow down (Heavy massed vehicles still go slower, but the increment of the slow down is less drastic than on other types of propulsion).

Also I know propulsion isn't a great word, I think I've seen 'motivator' used once.

Have you played Robocraft?  It has a good deal of these locomotion types.  Their hover is a pain to keep stable, easily tipped over, which makes for fragile craft if they take damage.

Turn radius might be a problem too.  Legs can turn in place, wheels, not so much.  Even treads can't really turn in place easily.  

37 minutes ago, Jordan Hoffman said:

I'm just imagining Gundams with wheels instead of legs lol.

It's more goofy to me imagining why someone would put legs or arms on a giant armored vehicle at all =)