[quote=@Claw2k11]
Is this still open for sign-up?
[/quote] It is, albeit the main continent is practically filled out.
You may discuss it with players to give up some of their land to make space for you or just try making a nation in the other continents.
Though it worths noting that in that case you'd be an ex-colony like Mexico, Canada or the USA. If you want possibly under a relatively minimal rule of the original owner.
I say being ex-colony is equally fun and besides you could be even something like US if you want. Just talk things out with whoever colonized you and possibly include cultural/technological elements from that player's nation.
So yeah, it may take a bit more effort to insert your nation but that's all.
You're welcome.