Assuming an implementation containing multiple puzzle branches (to offer players an alternative to Sokoban), have all the branches start from an “antechamber” level off the main dungeon. This is a small unpopulated level, and contains terrain clues around each puzzle branch staircase in it, such as boulders and strangely shaped walls for Sokoban, ice if there is an ice sliding puzzle, etc.
Sokoban puzzles that have no spare boulders by default can have a little attached room containing several easily retrieved spare boulders, but it incurs a Luck penalty to open the door to this room.
Prevent giants from accidentally moving on top of a boulder in Sokoban, which incurs a luck penalty. This is probably most easily done by only allowing them to move on top of an unpushable boulder by prefixing the move with m.
Another possibility is just to prevent giants from stepping onto boulders in Sokoban at all, giving a message “The ceiling is too low for you to step over this boulder.”
Add a game mode that spawns you in Sokoban on the stairs to the main dungeon. No monsters or items generate in this mode, it is just for practicing the solutions to the puzzles.
Grant an experience level or two for completing Sokoban without penalties (or with an acceptably small number of penalties). Also maybe a permanent +1 luck that never decays, like with a full moon. Possibly remove the rings and wands or the prize to compensate, since they make the branch effectively non-optional and it should be optional.
Remove the air currents in Sokoban that prevent you from floating or flying over the pit and hole traps. Instead, apply the normal luck penalty. Though it’s been pointed out that this would allow a player to bypass the entire branch and then negate the whole luck penalty if they can find or create a coaligned unicorn and throw a few gems at it.
Dungeons levels generate random, small Sokoban “rooms” - actually themed rooms, never on a path between the two stairs, possibly using “diagonaloban” rules which permit boulders to be rolled in any direction. There is a minor prize in each room at the end of the puzzle.
Internally, rooms like this should have their own room type, which will help with putting in anti-cheating measures:
It’s unclear what the methods to prevent the standard forms of cheating (breaking boulders, reading scrolls of earth, carrying boulders as a giant, etc) should be. Possibly they will just carry cheating penalties like normal.
Cut the length of Sokoban in half by excising the two middle levels. It is now a two-level branch consisting of a small, easy first puzzle level, followed by a tougher level with a zoo and prize.
Within Sokoban, boulders weigh 6000 for giants, just like anyone else, so you can’t carry them around.
Cheating in Sokoban no longer affects Luck. Instead, the amount of cheating you do is tracked; the quality of the prize item degrades the more you cheat. So a little bit of cheating might still give you the amulet of reflection, but a moderate amount would turn it into an amulet of ESP, and a lot of cheating would turn it into an amulet of restful sleep or something.
Prevent items from generating on top of the pits and holes in Sokoban.
Pushing a boulder costs d3 or d4 nutrition, in order to balance out its easy source of Str exercise. However, something would probably need to be done to compensate in Sokoban (maybe put even more food there?)
Sokoban is undiggable until the level is solved.
Fix the effective level difficulty of all Sokoban levels to either the level past the one with the stairs, or the level with the stairs, or a constant 9.
It’s a common refrain that Sokoban was too easy in 3.4.3 with its easier difficulty as you progress through it, and that it was too hard in 3.6 with its harder difficulty. Fixing it at a constant difficulty is a popular middle ground.
Sokoban levels with water or lava instead of holes (and make it so that boulders never sink without a trace in Sokoban). Air currents will still pull you down into the liquid if you try to go over them. Not specified what should happen if the player tries to boil away or freeze the liquids.
Sokoban is a one-level branch that strings together a bunch of different puzzles that must each be defeated in turn, all eventually leading to the treasure zoo. Obviously, the pits must be changed to holes that drop you on the level with the Sokoban stairs.
Rolling a boulder on ice makes it slide for up to 10 squares (provided it keeps sliding over ice) before stopping. If it hits some other non-ice walkable terrain, it stops immediately on that square. It is treated like a rolling boulder trap, capable of hitting monsters in its path. This mechanic could be used in Sokoban to create interesting puzzles.
Cursed potions of gain level work in Sokoban, but they always place you on the downstairs of the next level up instead of randomly, effectively letting you skip any level except the last one.
Move Sokoban much later in the dungeon, and make time not pass there. This Sokoban would consist of larger levels, but the boulder puzzles don’t cover the whole level.
Small room with a door near the start of each Sokoban level for you to place your pet in while you work.
Pets don’t go feral if you are both in Sokoban, even on different levels.
A “reset button” for Sokoban, which restores all the original holes and resets all the original boulders, and places the player on the downstairs (or is reachable only from the downstairs). Probably not activatable after the level is solved. Flavored as some sort of mechanism.
Give a Luck penalty for destroying a Sokoban boulder by polymorph shudder (or polymorphing it in any way, really, since turning it into anything else removes it from the map).
Modify Sokoban maps so that a monster can never get stuck in an awkward place except by the player doing something foolish. Possibly make the corridors leading to the goal double-sized or have alcoves off to one side where a monster can move.
Find some justification for making the flavor of Sokoban a branch where the ceiling collapsed and opened up pits and dropped rocks everywhere.
In variants that have multiple selectable Sokoban prizes, one prize is multiple random rings and a random amulet, but there’s no way to see what they are without sealing off the other prizes.
Sokoban provides a choice between an oilskin bag of holding and an amulet of reflection and magical breathing. Neither of these is very likely to generate randomly.
Instead of having Sokoban as a branch, generate occasional Sokoban puzzles in the Dungeons proper. It must not be mandatory to complete them to pass through the level.
All Sokoban levels add extra spaces to the corridors to let you push spare boulders all the way into the room if you so wish, which lets you handle monsters zapping wands of digging in the doorway or corridor.
Replace Sokoban with some other game like mahjongg. Instead of a pass/fail, you can achieve a degree of success. Doing really well nets you both the amulet and the bag, doing slightly less well lets you choose, but ordinarily you will get only one.
Replace the Sokoban rewards with something that is still nice but not AS nice.
Include a kitchen sink in plans that add a separate reward level above the top level of Sokoban, or in that level (so that anyone wearing a cursed ring of levitation there has some recourse to get back down).
Moving in Sokoban by jumping and hurtling from an iron ball doesn’t actually work to bypass boulders in 3.6, so it shouldn’t incur a Luck penalty.
