The first and only expansion pack for Dungeon Keeper was, I think, the first time I experienced true disappointment about a game I'd bought.
I'm not saying this to rag on The Deeper Dungeons or its developers: expansion packs were considered a necessity for PC games back then, and who knows what executive pressure Bullfrog-folk were under to quickly release something, anything, for their best-selling management-strategy combo.
I'm saying it because Deeper Dungeons (unfortunately for it) also came out at a time when my young tastes were busily switching from "it's amazing because it's a videogame!" and into something more discerning, more defined by unfair expectation.
The Deeper Dungeons was 'just' a pack of standalone new missions for a game I adored. Or thought I adored. But it turned out I didn't so much want to dig, well, deeper into the core experience, and instead demanded more story (such as it was), more monsters, more surprises. Novelty, not repetition. 2018 me, who likes to comb every last flake from a game's scalp, would probably have gotten much more out of The Deeper Dungeons than 1997 me. 1997 me tore through everything at speed then hungrily asked for more.
But, also, it was a lesson: loving one thing at the exclusion of all others (even if only for a time) can only mean disappointment. Getting more of what you think you want isn't the same as getting something you didn't know you wanted in the first place.
15 new maps! That'd be considered a damn decent DLC now.