I've kept an eager eye on production sim Rise of Industry ever since Leif tried, and failed, to build a whisky business in it last year. It looks promising, and the idea is that you control all aspects of whatever trade you want to pursue, from sourcing raw materials to sorting supply routes. According to developer Dapper Penguin Studios, it was the top selling game on Itch.io in 2017, and now it's broadened its horizons by entering Early Access on Steam and GOG.
It's a fairly deep sim, all told. You can choose to specialise in trading, production, gathering, or any combination of the three, and as you advance you research more efficient ways to do business. When Leif launched his whiskey empire he had to build a distillery, water siphons, farms, glassworks, and sandpits to make the glass itself.
You pick from 100 different products on a procedurally-generated map that changes over time. That field of grassland you were relying on might soon turn into a desert, for example. You're also battling against AI opponents who are trying to set up their own businesses in the same space, and you'll have to deal with random events like quests and contracts.
It's single-player only for now, but it will add multiplayer after launch. That won't be until towards the end of this year, once the team have added more products, more factories, bigger maps, a pollution system and more. The full development road map is outlined here.
The main limitation, from reading user reviews (and something Leif mentioned too), seems to be a lack of flexibility: you have to work out what the people of the world want, and what the environment is suited to, and make sure you cater to both of those things. As Leif wrote, "it's is all about figuring out what other people want, not what you want". That could put some people off.
If you want to give it a try, it's £16.99/$21.24 on Steam and GOG, which includes a 15% discount for the next five days.
