An artifact bag into which you can only put worthless glass. Invoking the bag either summons a shield with a damage-reduction buffer, or grants you temporary HP, equal to the number of pieces of worthless glass in the bag (which get used up).

Various proposals for things to happen on St. Patrick’s Day:

• Leprechauns should get buffed. There are various ways this could be done; probably the easiest is giving them more starting gold but also increasing the damage of their attacks.
• Leprechauns could spawn with potions of booze (always for individual leprechauns, low percentage chance in leprechaun halls). Ideally, the potion should be green.
• When random gold piles generate, leprechauns should frequently spawn on them.
• Random gems should have an elevated frequency of emeralds and green worthless glass.
• If the game is started on St. Patrick’s Day, the potion of booze is always shuffled such that it’s green.

When you identify a piece of worthless glass that belongs to a shopkeeper, they get angry and attack you because you have exposed their fraudulent business practice.

Glass objects should be eligible for forging, since the temperatures involved in a forge are more than enough to melt and recast glass.

Also, it should be possible to forge pieces of worthless glass together to make decorative ornaments, which are worth either score or can be sold for spare money.

The room of gems in the Castle should never contain worthless glass. (Unspecified whether it should still contain gray stones, or exclusively valuable gems.)

Colored glass frequency corresponds to its real-life frequency; red, orange, and yellow glass are rare; green and brown common, etc.

Shopkeepers will buy identified glass for the same few zorkmids they will buy it unidentified, rather than refusing to buy it, because it makes no sense that they buy it when the player doesn’t know that it’s glass and refuse to when the player does.

Dwarf and gnome kings will never pick up worthless glass or gray stones on the ground (they continue to pick up all valuable gems).

Archeologists (maybe gnomes too) start the game with all valuable and worthless gems (but not gray stones) identified. If this is too powerful, perhaps they only begin the game with all worthless glass identified.

New special room “ruined church” that contains ghosts, pieces of glass scattered around the floor, maybe an altar, maybe a spellbook, and blank paper/scrolls of junk mail scattered around the floor.