Inspired by a post on Kaden Ramstack's blog with a list of towerless Wretched & Alone games.
A couple years ago I made a twitter thread (followed by an itch forum thread) about dice substitutes for Jenga-style block towers, which were the main mechanic in (among other games) The Wretched, which had an active SRD jam on itch at the time. The issue is basically that dice towers aren't necessarily easy to come by, and they're almost impossible to do digitally with the tools we have at the moment. There are 3D simulations of block towers, but I've never found one that's anywhere near as stable as the real thing. So, I turned to dice. I posted one mechanic, and some people on itch suggested some other dice mechanics.
Caveat: as I say in the twitter thread, these mechanics are always gonna have different feelings to pulling blocks out of a tower. They're completely random, for one. They just reflect the ideas of a safe start, dwindling resources or survival chances, and a long, tense, ending (usually). None of these have the feeling of deliberately choosing a block and trying to get it out without toppling the tower, the tension of knowing it's all on you. That said, none of them need you to have precise motor control or even actual physical game tools.
Like I said, these mechanics are handy if you're playing digitally. That means you don't have to, y'know, limit yourself by what's physically practical. It'd be a pain to roll e.g. 100d6 in real life, but it's super-simple with a discord dice bot or online roller like orokos or even google's dice-roller tool.
Nat Barmore, one of the developers of Dread, the 2005 block tower horror TTRPG, described their experience with Jenga game lengths:
FYI: our math when developing Dread was:
10 pulls:guaranteed
20: almost always
30: most groups
40: many groups
50: every pull after this is a gift of the FatesTheoretical max is 105, but I don’t think I’ve ever seen 60.
This is for Dread, where you pull blocks and put them back on top of the tower. In Wretched & Alone games you don't (necessarily) do that.
A couple of these are slightly changed from the way they're written in the sources, just to make them simpler. They work pretty much the same way.
The simulations I plotted for this post are a mix of average games (showing how an average game using each mechanic would go) and game lengths (showing how many games reach each number of rolls/pulls/etc.). Both plots are built from 10000 simulations each. No error bars on the average game plots because I can't be bothered.
These are done with MATLAB. I should probably switch to Numpy or Scipy or whatever.
This is like radioactive decay. Your count drops fast at first, then slower and slower the fewer dice you've got (exponential decay). The tension rises with every roll later on, because you might be losing the one of the precious few dice you've got left. One neat feature of this mechanic is that because you have 100 things, and that count is always dropping, you've got always got a percentage number you can use in journalling. Percent of air left, or defensive walls un-breached, or distance to home, or whatever. You could also invert it, e.g. when you have 10 dice left, something in the story's 90% complete.
d10s aren't as common as d6s, so you might be able to do this in real life more easily than the first one. That said, the rules are a little more complicated.
This one's a little different. It keeps the dwindling feeling, but not the tense, drawn-out ending. It also guarantees the game'll be at least 10 turns long (since you can only loes 1 token per turn at most), which could be handy.
Straightforward and easily-tweaked by changing the starting counter, but it has 0 tension until the last few rolls and also needs some book-keeping.
Suggested here, you could use a d12 instead of a d6, which'd add more rolls that could end the game.
This one's maybe even less demanding than number 3, but it does need polyhedral dice and not just regular d6s. It also needs you to keep track of the number of turns that've passed, and it doesn't have any feeling of decay/dwindling. However, it does give you 2 numbers you could use somehow in your journalling (the two different d100 rolls).
Dominoes aren't super-common but this is a neat alternate and gives you a bunch of numbers (or shapes of pip patterns) that you can use while journalling if you like. This one does always end within 28 turns, though, and it's also super-unlikely it'll end before turn 20 (most games'll end on turns 26–28, even).
One neat thematic thing you can do with this: 28 dominoes in a set, about 28 days in a moon cycle, or 28 Days/Weeks Later…
This one has a kinda creeping feeling of difficulty and it's pretty easy to tune by changing the number of d6s. The only downside is (like some of the others) there's no sense of dwindling resources, or falling chances of survival. Like yeah you have a lower and lower chance of succeeding with every turn, but there's no visual for that (e.g. discarding tokens or dice or dominoes).
A neat mechanic with a dwindling feeling. It's a little bit complex, but you can use that complexity in journalling. Something's clearly either stacking up or being lost here, something you're actively keeping track of in the same medium you're writing your journal entries.
Well, basically they're (almost) all pretty similar. Most of them pretty much guarantee you'll get 15–20 turns before there's any real chance of the game ending, and on average they all end after 25–35 turns. Most of the average game graphs show exponential decay (including d6 vs tokens, which starts its decay after turn 15 or so).
The main things are:
whether a game's got a really hard limit (like the dominoes or 1d6-vs-countdown) or can go on seemingly forever. I'm counting stuff like 1d100 with advantage as “going on forever”, since it's got a high cap you almost certainly won't reach.
whether the game's binary or not. By “binary” I mean each turn you do pretty much the same roll and if it fails the game ends. The mechanics where I don't have an “average game” graph are binary, cause there isn't really anything to plot. The others measure your progress, like losing dice or tokens or crossing things off lists.
the exact stats, e.g. when you use the 100d6 mechanic, about half of the games end before roll 30, but when you use 1d6-vs-tokens, three quarters of games are still going by then.
That leaves other stuff like aesthetics, tools, tune-ability. I've talked about these under each mechanic—things like how easy or hard it is to tweak, and how you could use some of the numbers each mechanic gives you. Here are the ones I think're are easier to meaningfully tweak:
And here're the ones I think are harder to meaningfully tweak:
That doesn't mean these mechanics are bad, just that they're kinda rigid unless you're making big changes.
So, I guess, in conclusion, any of these is fine, just check out the graphs to make sure it's exactly what you want, and if you wanna tweak it, you might be better off with one of the five more-easily-tweaked mechanics.