Returning to the topic of simple mechanics with big impacts, consider the Test of the Obelisk in A Tale in the Desert. Most of you have never played, so let me explain. Some particulars may have changed between Tellings, so I am going with the one I remember best, from the original ATitD.
To pass the Test, you must build an obelisk. It must be at least 7 cubits tall, and it must be at least 1/7 larger than any obelisk within 1000 yards, and it must remain the tallest for a week. The building cost of an obelisk increases geometrically, mostly in bricks and boards but also involving ash, linen, and other materials.
It is the first and simplest Test of Architecture. The devil, as ever, is in the details.
Cooperation versus competition should be the first thing that you see. In an efficient world, there is some social process for deciding who builds where, when, and how big. With perfect spacing and timing, you save a lot of resources. If people build size 7, (wait a week) 8, (wait a week) 10, (wait a week) 12, … a lot of people pass a Test cheaply.
On the other hand, I might see that the largest obelisk in my area is 7 (you get a supernatural ability to detect that). Really, I can pass the Test for just 8 cubits? Up goes the obelisk! Oh, you built yours 6 days and 18 hours ago? Sorry about that/sucks to be you. Oh well, I’m passing a Test on the cheap, as long as no one … you built a 9-cubit obelisk? You jerk/idiot, that’s not even passing, but it stops me!
You can see how this could play out in a variety of ways. You have some people cooperating. You have some people competing. You have some people who are not in touch with the community and are unknowingly competing. You have some people who do not really know the rules and who knows what they are doing. ATitD is a hardcore social PvP game, and remember that other players can creatively attack you or potentially exile you from Egypt.
Digression: the course of this Test would change a lot without that supernatural sense of how how tall you need to build. You would ask around, build as tall as you think it should be, then see what happens in a week. Most obelisks would end up being decorative, and the required size to pass would lurch sporadically.
Let’s talk about those decorative obelisks for a moment. You decide that a huge obelisk would be just the thing to make your camp look awesome. In fact, someone did build a 1000-cubit obelisk, and I do not recall if that person had already passed the Test. With costs increasing geometrically, you can see how this was an expensive undertaking and how it made any future obelisks in the area much more expensive. Basically, the Test was closed in that region once someone did that. Smaller decorative obelisks were common and harmless.
Digression 2: when the bar is raised, it stays raised, even if you tear down the old obelisk. In a really efficient world, you build a 7-cubit obelisk, pass the Test and tear it down, then I build a 7-cubit obelisk, etc. The game rules do (did) not work that way. Nice try. Once an obelisk is built, it permanently affects Test passage in that region.
Let’s talk about those regions. While the text talks about 1000 yards (or however it was phrased), the actual programming divided Egypt into four areas of the appropriate size. You could build dead center or one pixel inside the border; the obelisk affected your entire region. (Building on the border still only affected the region that had the central point of the obelisk. Potential griefing averted.) It is important to learn the differences between what something says and what it actually does.
Explorer bonus: those four regions were based on a 1000-yard radius, and there were gaps between the circles. The first people to find those gaps got very cheap obelisks for themselves and/or their friends before word got out, and those at a time when 8/7* a large number was growing quickly.
There is an obvious advantage to building early, but not as big as you might think. Those first obelisks did not use many materials, but those materials were precious. The bricks were made by hand in wooden frames. The boards were planed by hand using slate blades that broke easily. The linen was particularly dear as it came at one of the early resource bottlenecks; using it to pass a Test cost a lot and kept you from using it elsewhere.
Later builders had some great advantages. Brick machines let guilds stockpile tens of thousands of bricks. Metal saws let you plane boards AFK. Cross-bred flax had higher, faster yields, and linen was all but free by the midgame. The numbers were higher, but the time to reach them was similar or lower. Some people knew about those sweet spots for cheap towers, but it was not worth the time to haul materials there rather than just throw more mud into the brick machine.
In the middling times, inter-regional strife about obelisk tourists broke out. (p>0.99 that I am the first human to type that sentence.) When it was worth it to haul your goods to a less populated region, people did. Residents of the less populated regions did not always appreciate that. A low obelisk height requirement was a sort of natural resource, and no one wants the big guild from up north appropriating their natural resources. Sure, it’s efficient for you.
Achiever penalty: almost everyone builds obelisks. Architecture is the most obvious manifestation of ATitD. Not everyone wants to complete Tests of Worship or Leadership, but crafting and building still are major ATitD draws. The Tests of Architecture are the most straightforward and most easily available. It was the first goal on your list, one you could complete collectively with friends or gradually soloing. It did not need to be the first Test you passed, but it naturally was for many. In a game populated by crafters, “build something big” was a big draw that led to big obelisks. This contributed to adding other obelisk types later in the Tale.
But ATitD is a social game as well as a crafting game, hence all the social and economic questions that arose from a simple building project.