A brief summary of Raid on Dwarka, Operation Trident and The Shark, all set in the Indo-Pakistani conflicts of 1965 and 1971.
In Raid on Dwarka (1965), you command a Pakistani squadron ordered to destroy a radar station in Gujerat, while luring the Indian naval forces at Bombay into range of a lurking submarine. By keeping your force (submarine apart) together, it is not hard to destroy some minesweepers, crush an outgunned pair of Indian frigates that approach from the NW and take-out the radar. More Indian ships then approach from the SE (light cruiser Delhi, a destroyer and two frigates). Attacking these with the submarine isn't easy and the cruiser eluded me (disappearing in plain view). The sub was later able to sink one of the frigates. The destroyer came in ahead of the cruiser and my ships were able to concentrate on and sink it. At this point, the AI threw-in the towel without the Delhi firing a shot.
Operation Trident (1971) sees a modernised Indian fleet mount a raid on Karachi with Osa missile boats. It's basically a straightforward exercise, as the Indians have better sensors and better weapons and can defeat the patrolling Pakistani ships in detail. A good scenario for beginners.
The Shark (also 1971) is much more of a challenge and can be played as either side. Two Indian frigates are detailed to sink a Pakistani submarine, which has betrayed its position by breaking radio silence. They are helped by two pairs of ASW choppers.
Playing the Pakistanis, I had my only success to date against an ASW chopper, but I was lucky. Got within range of a frigate, only to be detected and attacked before I could fire. Thankfully, one ASW torpedo missed (on 60%) and the other was launched too far away. Not helped by having to recharge my electric batteries, I then had a long game of cat and mouse with the frigates. Wonderfully, they could outrun the sub's torpedoes and, try as I might, I couldn't get close enough to ensure a kill. It looked like a Minor Victory until the frigate Khukri inexplicably reversed course into my last torpedo and was sunk. As I said, I was lucky!
Incidentally, the Pakistanis can 'win' just by avoiding contact and running away, as a score of zero is a Minor Victory for them. Not much of a game, though...
As the Indians, I found it very hard to detect the submarine, despite using interlocking search sonars as far as possible. Eventually, the sub revealed itself by attacking. Outran the torpedoes and was then able to home-in on the likely launch location. The choppers, which have endurance issues, have to deploy their dipping sonars, then hover directly over the sub to use their short-range torpedoes (best done in pairs which, happily, you have). With this done, two 'tinfish' did the trick for a Triumph.