I love me some OpenTTD, except for two parts of it. The first is the tycoon part. The central conceit that you open up a brand new firm in some town and then proceed with major infrastructure projects is kinda silly. If there was a mode where the cities on the map gave you open-ended quests/goals (like move N number of passengers per month between our two cities etc) and then you had a budget to accomplish it, I'd play the shit out of it.

The other thing is the pricing model. As things are now, it doesn't make sense to connect a coal mine to the power station right next to it, since you're paid by distance traveled, not for the efficiency of the connections you've made. This results in silly shit like having to move steel across the map to maximize profit. Of course, you could read this as a subtle condemnation of the capitalist mode of production, but really it's just a poorly thought out gameplay element.

I'm also not too hot on the size scaling of roads/railways and buildings, but this is a staple of tycoon games so I'm willing to roll with it. In any case, it kinda sucks that a single railroad track takes up the same space as two lanes of automotive road, and also the same size as a a house/apartment building. Of course, you'd probably need a brand new engine if you wanted to make more realistically proportioned maps so...