I think this is a bit like how US people call orange-fleshed sweet-potatoes "yams". If I understand correctly, the orange-fleshed sweet potatoes were introduced

I think this is a bit like how US people call orange-fleshed sweet-potatoes "yams". If I understand correctly, the orange-fleshed sweet potatoes were introduced to the market later than the white-fleshed ones and there was a need to diversify them the better to sell them as something new, so they were called "yams" by sellers and growers, I suppose. This is confusing because "yam" is a completely different plant: Although the soft, orange sweet potato is often called a "yam" in parts of North America, the sweet potato is very distinct from the botanical yam (Dioscorea), which has a cosmopolitan distribution,[8] and belongs to the monocot family Dioscoreaceae. A different crop plant, the oca (Oxalis tuberosa, a species of wood sorrel), is called a "yam" in many parts of Polynesia, including New Zealand.[9] https://en.wikipedia.org/wiki/Sweet_potato#Naming https://en.wikipedia.org/wiki/Sweet_potato#Naming And of course sweet potatoes, of any kind, are not potatoes at all. It's just a name that people give it that sounds familiar and that perhaps helps figure out how to use it. For "roguelikes" (or "rougelikes"? That seems to be an established spelling now) I think one important effect is that it helps direct gamers who hate permadeath away from games that have it.