Developer House House and publisher Panic announced today that their co-op multiplayer puzzle/exploration/goof-around game Big Walk has achieved huge sales success in just under a week. In a post on Bluesky, Panic announced that Big Walk has already passed over one million units in sales. For small development teams and publishers, one million is a tremendous milestone–one that plenty of big commercial releases from major publishers often fail to reach. But we’ve seen a fair few massive indie hits in…