It took almost as long to download as the cargo ships mod, which has a ton of stuff in it. Is it the graphics resolution?

It's the graphics for the wagons. They're responsible for 38.6MB of the total 38.9MB of this mod.

There's 256 rotations for the wagons, and two resolutions (low and high). 29.9MB is from the high res wagons alone. This is about the same size as these sprites in the base game, but I have to include my own copy to get the colors (I tried adding my own layer with just the new color, but that ended up looking bad and not actually saving much space).

So yeah, wagons are a pain with how many rotations there are, which is also why trains look so great in this game!

I see. Thanks for the info.

Still have no idea what it looks like, I haven't built any defenses yet (very low biter levels and I've blocked my pollution from leaving my base using Bio Industries).

:)