The top -down perspective with a large tiled playfield and big sprites gave the game an old skool overhead Amiga shooter 'look and feel'. The tracker style music helped with this as well.
It is extremely easy to pick up, but the mechanic is much deeper than it seems. One thing is to have blobs of ink behind you, but because the ink blobs stay, you can preplan an escape route (slide yourself quickly away or slide the crabs against the wall) while entering an enemy hotspot. This add an layer of depth which is quite original.
You could take this to the next level with having multiple competing Octo's or teams of Octo's in one arena, so you can drag the crabs towards each other. And have the WASD shake expel the treasures to steal while they are busy escaping. I think that would be extremely fitting as a couch game.