This is annoying if you have entered in a group by accident and you cannot leave without driving it away and breaking follow orders.

Good point, I can see why that would be annoying. You can change the per-player settings so that ‘enter a vehicle from a spidertron’ is done with U instead of overriding the vanilla Enter.

Do you think I should also add a ‘Allow spidertrons to enter other spidertrons’ setting?

Make it optional. Personally, I think trains are the only thing they should be able to enter because of physicality and, following that, it would look far cooler if they used their legs to hold onto the train instead of looking like they are shoving themselves in it.

Ok, I’ll look at adding some settings to configure which types of vehicles can be entered.

Getting the graphics working for ‘legs attached to the train’ would be pretty much impossible, and certainly beyond my skill. The train sprites get rotated in all directions but the spidertron lower-body and leg graphics are never rotated, so it isn’t possible to rotate them along with the train.