Ok so I've been gone for a while and one of the new features is Whistle.

My question is can objectives still be completed by only using the T hotkey or is exploration of the maze still required for the objectives?

you have to explore to do the quests

You gotta explore for almost all of the objectives

Bits and pieces and Hack the horde can spawn from a whistle, but you must have explored a bit first, not really sure how that works..

Thanks guys.

Don’t forget shamans.

You can spawn them but they need to be active. Only maze is active at level 1 so can't see them doing a 1-71 whistle.