Here are the complete level codes for Zeewolf 2 -

 1) START       7) -         13) -            19) -          25) GLOBOFF
 2) REQUIN      8) -         14) STATION      20) DOITNOW    26) BEHAVE
 3) WOLFRAM     9) STAG      15) -            21) -          27) -
 4) FULLMOON   10) -         16) GBULL        22) -          28) SHADOW
 5) -          11) KRAKEN    17) -            23) SHIPDECK   29) MAXFUEL
 6) OURAGAN    12) -         18) STATIPAUSE   24) -          30) PELPAY

 31) DOMINO
 32) STEERDART

 Tip - Last level STEERDART.

 Ignore the kestrel plane and the bomb, fly North east ( top right ) to the
 enemy base. Avoid battles with the enemy planes and fly round the perimeter
 of the base using homing missiles to take out the anti-air cobra placements.
    Keep at the base taking out as much as possible with all weapons when your
 homing missiles run out, do this until you die. TRY NOT TO ACTIVATE THE ENEMY
 ZEEWOLF.

 When a fair chunk of the outer base is taken out fly farther in and concentrate
 your fire on the grounded enemy zeewolf. It is much easier to hit whilst it is
 on the ground ( obviously ) and it won't shoot back. Once the enemy zeewolf is
 airborne it will chase you out of the base area and return to the centre of the
 base. It is during this time you should go all out and pile loads of lead into
 it. If it returns to it's base you should try to creep up on it avoiding any
 remaining cobras if possible, it should chase you off again.

 Keep trying this method and you should succeed eventually, it took me ages but I
 can do it nearly every time now!