Dowry gives you one-shot "infinite" buys, and then turns into a Victory card depending on the total cost of the things you buy.
Workhouse can be trashed for +Actions, but also offers Museum-styled VP for cheap-cards--including the Shelters.
Commons lets you put gained cards into your hand, or save cards you're trashing. Maybe it's the key to the others.
I think all of these are above the power level I would want for Shelters, but Commons is the worst offender. Just imagine Commons/Lurker. Or Commons/Bishop, which can reliably generate 8 VP per turn, or multiples of that with only some draw and actions.
I suppose I've read the challenge differently. It seems to me that Aquila was complaining that the Shelters seem to make very little difference to the strategy or play of any Kingdom. These aim to make a big difference. Hypercube's Sanctuary is a favorite of mine among those Shelters submit thus far, and probably makes the biggest difference on the average board (ignoring raw acceleration that I will cover in one moment).
While Commons is worded poorly, I've come to agreeing, not so much on its overall power, as its general dullness around Dowry. It's neat in that it lets you keep re-trashing Workhouse, but being able to re-use Dowry should be an oddity. I've nerfed it awfully to only swap out for newly gained cards, which has some tricks but not many. I'll probably swap it out for something else.
Hole
Types: Night, Shelter
Cost: $1
Trash this. If you do, trash a card from your hand.
Stick
Types: Treasure, Shelter
Cost: $1
$0. You may trash this to trash a Treasure in play.
Cove
Types: Action, Duration, Shelter
Cost: $1
Set aside 2 cards from your hand face down (under this). At the start of your next turn, put them into your hand.
Sanctuary
Types: Night, Shelter
Cost: $1
If you have at least $4 unspent, trash this and any number of cards from your hand.
I think players here are vastly underestimating the acceleration of trashing 2 of your worst cards on turns 1\2; Cove in the most swingy fashion because a Turn 2 Cove will be ridiculous. Like I said, I like Sanctuary, but it should probably trigger on $5, not $4. If you won't take my word for it, how about Donald X.'s?
Hovel is the only one that changed. Originally it was an action you could trash by discarding your hand. It turned out that trashing it turn 1-2 usually seemed like the correct play, even if you drew it with four Coppers. So that was no good.
Allotments
Types: Victory, Shelter
Cost: $3
˝VP
Lost Place
Types: Action, Shelter
Cost: $0
Trash a card from your hand. If it is a Curse: +$2, else gain a differently named card with the same costs.
Players lucking into starting with a $3 card instead of Allotments doesn't sound like a lot of fun.