Fantasy Zone II - The Tears of Opa-Opa
Platform: MSX 2
Region: Japan
Media: Cartridge
Controller: Keyboard
Genre: Shoot 'em Up > Horizontal 
Gametype: Undefined
Release Year: 1987
Developer: Sega
Publisher: Pony Canyon
Players: 1
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Fantasy Zone II: The Tears of Opa-Opa is the sequel to Fantasy Zone, in which you control Opa-Opa, a pretty colored ship with wings on its side. You must destroy the large creatures in each world before moving on to the next. Your task becomes difficult by other small creatures that happen to pass by. If you destroy a large creature, they will drop a dollar bill, which you can pick up and use at the shop to buy items and powerful weapons such as laser beams, x-way shots, and big wings. Another way to get money is to shoot certain kinds of enemies all in a row.

More often than not, some large creatures will reveal a warp gate rather than a dollar bill. You can go through the warp gate to get to another part of the land, and destroy more large creatures. Only one of them will have a warp gate in the form of a 'stop' sign - that is your ticket to the round boss, but you must defeat all large creatures in order to pass through it. Also like in the original can you walk on the ground to avoid approaching enemies, and spend money in the shop to get new weapons (but they only last for a limited time).
 
http://www.mobygames.com/game/msx/fantasy-zone-ii-the-tears-of-opa-opa