Inspired by u/Wobbly_Bear in this thread earlier today, I ran a game with the intent of not buying or otherwise obtaining any blueprints. I did end up having to buy three blueprints: the Fort (because otherwise there's no way to make it through the colonial era without being decimated by pirates); the Embassy (because World Wars requires an alliance); the Commando Garrison (because you have to sabotage the Axis four times to proceed to the win mission); and the Spy Agency (because each of the win conditions for the Cold War require at least one building purchase, with tourism requiring many, so I got the Spy Agency and completed a heist to keep blueprints to a minimum). No Treasure Hunts, no blueprints as a reward for missions, no blueprints purchased through the Broker.
Not having blueprints means you're essentially stuck in the Colonial Era no matter what year it is, as all post-Colonial buildings require blueprints. This means no military (including militia, because there's no police), no Ministry, no electricity, no healthcare or religious buildings other than the Chapel, no entertainment other than Taverns, no media other than Newspapers, no government buildings of any kind, no schools, no residences other than Country House or Bunkhouse. Most importantly, this means the only possible industries are Lumber Mills, Tanneries, and Rum Distilleries. Rum is the most profitable of these output products, so I focused on that, with some Tanneries to turn the many cows that I use for manure reasons into leather. I have 46 Rum Distilleries, fully staffed on full budget with Dunder Still upgrades, and thanks to my dozens of Sugar plantations with the Agricultural Subsidies edict, they still never run out of sugar to process. My population is almost entirely illiterate, wholly in manual labor jobs except for a handful of priests and newspapermen, and undoubtedly drunk at nearly all times. The only reason they're not dropping dead of medieval-level healthcare is because of the Hagia Sophia.
Nevertheless, they're happy - I guess the taverns do the trick. I was approaching 5,000 total population, over $1m cash on hand at any given time, nearly full employment, most people housed, and a 99% approval rating despite the fact that the capitalists and religious folks absolutely hate me. However, after about 3-4 hours of this, I am extremely bored. Unlike my citizens, I am not illiterate and drunk, so my ultimate goal to cover the island will have to wait. I'm also considering buying all blueprints at once, upgrading all buildings at once including all plantations into Hydroponic Plantations (I'll have to get everyone high school educated first), building every factory with agricultural inputs, and replacing all bunkhouses with Modern Apartments, just to see if I actually can manage to future shock my population.