A bold choice in name, that name holds a lot of memories of a great map... let's see how yours holds up to that name!
Honestly I don't care for the name. When you say "Hey man, let's go play some Valhalla," everyone's thinking of the other one, guaranteed. I'd recommend changing it to something else, maybe ice-themed, or related to "melting".
Well I'm not gonna lie, the word sounds pretty cool, and it retains the viking theme from "Valhalla." But it's an old word meaning "cat hole," referring to the size of a shallow peninsula, and I'm not sure that an icy canyon has much to do with that. Meltdown refers to an emotional outburst while also being an ice pun. My suggestions: *Cooler Heads (opposite of people having meltdowns) *Icebreaker *Flake Out (actually, that could be easily confused for Lockout and Chillout, so scratch that)