Six skulls - Ryoko's getting more devious with his hiding places.
Kindred Spirits provides substantial combats, including what may be a bolstered version of the cyborg. The drones are back too. The levels show off with intricate architecture that bolsters the gameplay. 'Dr. Tycho's Castle' comes off particularly strongly.
Kindred Spirits uses the dull Infinity textures but that's mostly a matter of opinion. Durandal hits us with a side of his personality we haven't seen before, specifically the "I'm thrilled to see you but I would never admit it." At any rate, he doesn't sound quite the way he does in other scenarios.
Another great pack!
A three level (plus one intro level) mini-scenario for Marathon Infinity.
This scenario is a sequel to Marathon Phoenix, although it is not as difficult. The player is reunited with Durandal, and the two follow the path of the UESC Atreides to a distant Human base.
EDIT 2/11/2014 You will probably need the Previous AI plugin to make this work! http://simplici7y.com/items/aleph-one-previous-ai