the steam engines were fun, you have to regulate the amout of steam, water and coal ratio, tank water level etc. doing the oriental express in full is still an epic journey.
or try going downhill in a Dash9 80car consist without going over speed...a mere 5mph more will get you a derailment.
I've tried BVE as well, the picadilly line was nice, the quality of the add-ons does flutuate though, and the site is slow as hell.