Name:  Conquest Earth

 Enter codes on the screen where you choose difficlty
 KICKS BUTT - go on 5 level
 TRIFFIDS   - go on 10 level
 JUPITER    - go on 15 level
 BIG GREEN MONSTER - go on 20 level
 H G WELLS  -  go on  25 level
 TRIPOD     - go on 30 level