Two new weapons: Boxing gloves and Roundhouse Kicks.
Boxing Gloves: Powerful and quick, but can only attack adjacent rocks in four directions (up, down, left and right). Super precise but might be difficult to build yourself a path out. Has both speed and damage passive effect upgrades.
Roundhouse Kicks: Begins as a weaker battle-axe. However, it continues to kick even when using another weapon. It also has both spin speed and damage passive effect upgrades (and yes... both are infinitely scaling).
Three new professions: the Martial Artist, the Shotgunner, and the Generalist+
Martial Artist: Dual-wield the two new weapons, your roundhouse kicks and your boxing gloves, to MMA your way to the centre of the Earth.
Shotgunner: Probably the biggest challenge so far. Can only use shotguns. But no platforms or ladders... or jetpacks... or wings... or hoverboards... or jump passive effect upgrades... or recoil passive effect upgrades... or employees... Good luck :)
Generalist+: A continuation of the Generalist - has access to use all the new toys from the latest updates as well as everything else.
Some performance improvements, including improving how the sparks are generated by pickaxe strikes (may be noticeable at high pickaxe strike rates).