Popular games built on game engine Undum

You stagger up to its lair. Blue sand drags at your feet. Your hands don't tremble — well, much — as you ready your new weapon. Your voice doesn't quaver (hardly at all) as you shout out the words you were taught. One, two! Dive and roll! Jump! Attack! ...That wasn't so hard, was it? You defeated the monster, and it's not even bedtime yet. A work of interactive fiction by Andrew Plotkin.