Basically support for air, space, sea and land vehicles. Just like in SP and KSP.

You could make à fuselage block empty and adjust the thickness of the walls and chose where the opening Will be

I believe that adding realistic physics for wheel/tire damage would be a great addition to SR2. For example, after being used for a long time especially on terrain that the wheel-type isn't designed for, or if the tire gets punctured, the tire could deflate. Or possibly the wheel could pop of from spinning for long amounts of time. I would really appreciate it if this idea were considered as I have always been obsessed with the numerous possibilities but limited physics of the resizable wheel in SP.

I think it would be valuable to have switchable command modules in one craft. For example, in the Apollo XIII mission, they were able to switch control between the lunar module and the command module.

after landing to earth you can't reuse your vehicle anymore. With this suggestion you can recover your vehicles, boosters, space planes. You can add a price to recover, example: if you land to ocean or land it will cost money but if you land to runway or landing pad your rocket will be free to recover just like spaceX did it with falcon heavy. If you see this post devs, please add this feature.

It would be quite great to be able to go back in time to a separation and control the other module. This way recovery missions would be possible.

For a game of this kind tripulated missions and science should be keys.

I think it would add quite a lot to the gameplay to make cockpit and habitable modules with interactive interiors, so you can move around, go to the pilot sit and have all the controls, screens with info... or go to a lab, go to a bed, pick objects and interact with them (use a microscope, a material analicer, move resources for ISS like storage...)

If you go crazy you could even add VR(?)

Add a system thing that can auto land your boosters when u detach them

Like propeller engines and jet engines (propeller engines would put you one step ahead of KSP)

Just to do Spacecraft or aircraft carriers, it will be very nice because we can build spacecraft carrier and send some planes on it to go on moon, mars ........, or if you cant, make alternative please, it can be just a magnet platform or something like this))) from SP and jundroo fans

have a 'block' that when launched to orbit allows you to create an orbital shipyard that you can launch from, you could make it really hard to get this piece into orbit so that only themes skilled of pilots are able to do it

You should be able to make your own planets with pre made assets, and have like a slider or a terrain editor where you can adjust planet size, atmosphere and soil composition and allow to make different textures

You could make the game more realistic if you could add part failure as a mechanic.
For example:
- Engine ignition failure.
- Fuel flow failure ... etc.

"Part Failures" could be added as an option in the game and not an
in-built part of the game so that people will have the option to play the game normally or in a sort of "Hardcore Mode".

Please kindly consider this suggestion. (Comment too.)

What i mean is that yo can chose solid/liquid the weight and how much thrust it produces along with maybe the chemical compostion or some other stuff then you can name the fuel and either use it on your craft or share it with friends! If you made the fuel a higher wait it might increase the thrust for instance so you couldnt just make wait 1lb and thrust 99999999999 newtons, it would calculate how heavy 99999999999 newtons would be.

tl;dr
custom fuel types
weight+ = thrust+ or something like that
plus selecting liquid/solid/some other types of fuel.

Remove the upvote system it results in a huge amount of useless threads. Hire a moderator or find a volunteer

Modding potential is already limited on simple planes with it's out of date unity version why don't we change that for SR2??

Everyone's we want simplerockets 2 for Android IOS and other mobiles