Greetings Omnimaga! I came up with this idea a few days when I was thinking of the world layout for another project of mine, Rebirth: The Soul of Icarus.  Basically the title says it all: it's a Spiral Knights clone.  I'm not sure of sprite size just yet but I've started thinking about some of the concepts story and gameplay wise.  It will be, of course an ARPG except it will be set in a Greek/Roman/Fantasy mythology mashup world. Backstory and Background information:
Vulcan, the Roman equivalent to the Greek god Hephaestus, the blacksmith god, created a special labyrinth commissioned by Zeus in order seal away the mountain Olympus, which fell to Earth after Hades corrupted it.  Eventually, the whole labyrinth became corrupted as well as the fallen gods and it merged itself with the Underworld.  Your goal is to explore this mysterious labyrinth, defeat the corrupted gods, end the reign of Hades, and restore Olympus.  The world's survival depends on your success.  But don't worry, you won't be alone.  Many other soldiers have also taken up this cause and will work alongside you on your mission.

So yeah... my current vision is to make the game endless.  Meaning that-you-may-have-reached-the-center-and-fought-all-the-bosses-but-your-quest-isn't-over sort of endless.  Hopefully I can make it expandable with expansion packs and new quests and side-missions and maps and whatnot.  Yeah.. it's pretty ambitious.  But I do hope to finish Rebirth first though.
Thoughts? Comments? Oh, and do you think it would be better off as a community project?

Yes the "MMO" part will be removed and it will be single-player.  I understand what you mean about the engine and you are right.. I should get that down before I get too ahead of myself.  Instead of a community project I could simply make it open-source but it will still be my project.

Yeah I agree with the open-source idea. As for MMO I would say avoid it for the time being and focus on single player. However, it wouldn't hurt to experiment once the entire game is finished in case a MMO is actually possible on-calc. I wouldn't be surprised if it did via gCn to a much lower scale, but it would be a lot of work because a multiplayer game involves a lot of extra things to check (such as extra balance issues, how easy it is to hack the game, where data gets stored (assuming it's even possible at all via Calcnet to send data to a server or something).

Yes the "MMO" part will be removed and it will be single-player.

The plan is for it to be a single player game.  I do plan to get to it (this year) and complete it but first I'm going to work on Rebirth: The Soul of Icarus first so that I will be prepared for a much bigger project such as this.