The Witch of the Tarriswoods is an OSR module from John Fredericks and Sharp Mountain Games. It's a short low level (3rd or so) adventure meant for Basic D&D, though of course it works reasonably well with any OSR game. It does seem to rely a lot on both ability checks and open doors checks, for what it's worth.
The plot is fairly simple (and there is one, it's not a sandbox), basically the town of Adela is having problems and it's up the PCs to solve them. As can be guessed from the title, the problem is the doings of a "witch" (actually a 5th level MU), who has unleashed (perhaps somewhat unwittingly) an evil at a ruined shrine in the woods. So the PCs must go to the shrine and solve the problem.
On the way they have three encounters, one involving the rescue of a farmer, one with skeletons, and the last is really more of an obstacle that they must get through using ability checks. Once they reach the shrine, it has two small levels, the first with 5 areas and the second with 3, including the final showdown with the witch.
