The Tavern

I've been playing this game since "Elf" was still a species, I have plenty of wins under my belt, and I can say I've traversed the Vaults and Elven Halls many, many times. And despite that, today was the first time I've *ever* run into a wizlab. (Lehudib's Moon Base, fwiw)

And I loved it! It was great! I haven't been so excited in a new area since the first time I tackled the Tomb. It was thematically really cool, it was challenging, it had all sorts of neat unique monsters that I had to learn how to deal with, and it was just a really fun, intense area in general. It's really a wonderful exhibition of the Crawl Dev Team's skills and dedication. So why are they so rare?

Compare wizlabs (or at least the moon base) to something like the Labyrinth. I'd estimate that the Labyrinth pops up for me in 50% of the games where I complete the Lair and the Dungeon floors, it's an absolute no-brainer in terms of loot (very low risk, quite good reward), and it's not even particularly interesting (though I do like the vaults that have been recently added, gotta say). Meanwhile, Wizlab has popped up for me, what, 1% of the games where I've cleared both Vaults and Elf? It seems to have a decent risk-reward ratio: it was harder than the Vaults around it, being quite challenging - the Moon Troll would've turned me into a pile of toilet paper if I didn't have a wall of summons to retreat behind - and the loot, while offering an excellent unrandart, gave me 50 gold and a wand beyond that. So it doesn't seem rare to me because it would be "too good" for players to get it more often.

As someone who's seen literally everything else the game has to offer (hell, I ran into the Desolation about a week after it was added), I'd really, really love to see more of these. Or am I just insanely unlucky?

They're not especially rare at all, you presumably just reach that point in the game less often. In fact they are more common than Labyrinths (assuming you visit every floor they can generate on), since they have exactly the same chance per floor as Labyrinths do, but have more potential floors to spawn on.

Wizlab can also generate in Depths (and Crypt too IIRC, though I rarely do Crypt).

Is there a way to check if there is some bug? I agree with OP, Wizlabs are generated much less often than Labyrinths.

I have just checked my offline wins. I entered 45 Labyrinths and only 31 Wizlabs. I often cannot reach Labyrinths in time but almost never miss Wizlabs (there are usually scrolls of mapping at this point). I explore Crypt/Elf in almost all my games.

Clustering illusion, I guess.

For example, I always get the useless Iskenderun wizlab, despite the fact that I play spelless like 95% of the time.

So I got curious and checked my last 37 victories. I always try to reach timed portals and almost always succeed. I remember twice missing a wizlab and a couple of games were more than one portal were on one level and I only reached the first one. Then again, I don't know if those were winning games...

Anyway, the stats:
Bazaar: 33 bazaars in 24 games
Ice Cave: 27 times
Labyrinth: 19 times
Volcano: 11 times
Wizlab: 10 times
Sewer: 10 times
Ossuary: 9 times
Trove: 9 times (I miss out on Troves a lot, when the fee is 8 !HW etc.)
Bailey: 9 times
Desolation: 1 time (of course this is new)

What stands out is that Ice Cave is much more frequent than the others. Lab seems to be clearly more frequent than the rest. The others seem surprisingly uniform.

Wizlab entrances vaults are much bigger than the labyrinth entrance. Is it possible that levelgen is often unable to place them?

EDIT: milestones for awbw (won cv=0.19 br.enter):48x Zot:1, 28x IceCv, 18x WizLab, 17x Lab, 15x Sewer, 13x Bazaar, 12x Bailey, 11x Ossuary, 10x Trove, 9x Volcano, 8x Desolation,

EDIT2: 4237 milestones for * (won cv=0.19 lastmonth br.enter): 250x Zot:1, 130x IceCv, 109x Bazaar, 101x Lab, 81x Trove, 67x WizLab, 57x Bailey, 55x Ossuary, 50x Volcano, 46x Sewer, 41x Desolation