[DrBeast]

Freeze Time is highly recommended, but alas noone has suceeded in creating it :rotfl:
Seriously now, the only mod I can recommend for such short playing times is Reflections On The Water (ROW). Doesn't alter gameplay in any way, but it gives eye-candy aplenty. All the major mods out there [Trigger Maru (TM), Real Fleet Boat (RFB), Run Silent Run Deep Campaign (RSRDC), Natural Sinking Mechanism (NSM)] aim for a more realistic/prolonged gameplay.