Fantasy Zone has an interesting history.
Being released on various platforms in the 80s and a few re-releases most notably SEGA AGES 2500 series and Fantasy Zone Complete Collection both on PS2 and most recently a 3D Classics port for 3DS where it was given an updated title:
Fantasy Zone: Opa-Opa Bros as it introduces a new playable character Upa-Upa in System 16 form.

This run is the Sega Master System version aka SEGA MARK III played on a Wii as the Virtual Console release supports turbo. This leads to rapid fire abuse, saving a huge amount of time in the entire run.

* Sega Master System will be shortened to SMS in my comments below.

Notable differences:

Base count per stage:
Arcade 10
SMS 6
First purchase price for upgrades

Name	Arcade Price ($)	SMS Price ($)	Difference ($)
Big Wings	100	100	0
Jet Engine	1,000	500	-500
Turbo Engine	10,000	5,000	-5,000
Rocket Engine	100,000	30,000	-70,000
Laser Beam	1,000	500	-500
Wide Beam	500	1,000	+500
7 Way Shot	5,000	2,500	-2,500
Twin Bomb	100	200	+100
Fire Bomb	2,000	1,000	-1,000
Smart Bomb	2,000	1,000	-1,000
Heavy Bomb	2,000	1,000	-1,000
Extra Ship	500	2,500	+2000

 

Tricks used in the run:

Unlimited Power up weapon time:
Feels more like an easter egg rather than a cheat code. Heck this trick even got mentioned in the hint sections of the US instruction manual.

You need to purchase all 4 engine upgrades and then buy any SHOT power up. After selecting a powerup, the time limit lasts forever until you lose a life.

Quick boss spawn:

A small trick that saves nearly 8 seconds per stage. You need to:
1) Destroy the final base
2) Collect the coins,
Sadly it isn't as simple as that for the later stages because there's more enemies, projectiles and coins to deal with and if you pick up too many coins, it will spawn a SHOP balloon which actually delays the boss spawn even more! I do this trick in the 6 out of the 7 possible stages. The only stage where I don't do the trick is stage 4 because of a strat I use in that level.

Quick shop exit:

Very situational depending on money count after stage 4 shopping. I purposely use up all of my money on Fire Bombs and if the money is low enough to not buy anything else, it will take me out of the shop much sooner.

Weapons:

Laser: Probably intended for players not using turbo as this weapon's rate of fire is fast but turns out to be weaker than a turbo mode twin shot.

Wide: Covers a good area and deals more damage than twin. Used in stage 3 to save money not having to buy 7 way.

7 way: The main weapon of choice from stages 2, 4-8. It covers a huge area and deals incredible damage per second.

However, due to lower, inferior specs of a SMS game, most of the time it will cut down to a 5, 3 or even 2 way spread. When that happens, there is a chance Opa-opa collides towards an enemy from slightly below and loses a life; all thanks to the weapon unintentional downgrade from 7 way to 2 way. Another problem: It is not possible to point blank fire and damage any bases in stage 4 as the middle part of the 7 way shot goes straight through.

Fire Bomb:
Absolutely mandatory in Stage 4 as it goes along the X-Axis and destroys any non-boss enemy making contact. It is slightly useful in stage 5 killing a set of enemies after the 3^rd base.

Heavy Bomb:
If Fire Bomb covers horizontal space, then Heavy Bomb covers vertical space. This weapon is useful against Cobabeach and the last two aliens in Round 8.

Smart Bomb:
Destroys all non-boss/non-base enemies with a full screen flash. Sounds awesome, but the other two bombs have their uses and if it was possible to auto switch from Heavy/Fire to Smart it would be very useful for rounds 5-7 to clear annoying enemies. Sadly after using Heavy/Fire it auto switches to Single Bomb making this bomb completely ignored due to the route for a good speed run.

Stage by stage comments:

Round 1: Plaleaf

Very straight forward level, only losing a couple of frames from the small coin drop thanks to an enemy by base number 6, it's actually not a huge deal as there's potential time savers later on in the run that isn't always guaranteed.

VS Stunpalon.

According to the hints section of the US Manual it requires 16 twin shot hits to destroy it, even with turbo it isn't possible to one cycle the boss.

Round 2: Tabas

Now both Rounds 2 and 3 I am allowed to have a small room of error after entering the shop as the real optimisation starts in Round 4. In order for the shop to appear in Round 4 I basically need to get rid of my Power Up Shot weapon.

For this stage I buy the following:

Jet Engine
7 Way
Twin Bomb.

Now technically I have enough money to get a Turbo Engine but there are a few downsides to that as it will require switching items in the menu during Round 4 and it actually does not save time for Rounds 2 and 3 due how SHOP spawn works.

The key to quick spawn this boss is right before Base 5 or 6 there are 3 Coulon (yellow planes) it's best to get rid of them, pick up their coins and then destroy the last two bases.

Vs Volanda

Volanda has got severely nerfed in the SMS release for many reasons:
* The main barrier's collision does not exist until a few seconds later, enabling the player to shoot two bombs or a few 7 way shots.
* Life orbs is now 3 instead of 8
* Less projectile pellets falling down = easier to dodge.

Round 3: La Dune

7 way is about to run out, so I try and destroy the first base and pick up the coins right after losing the weapon to spawn the SHOP balloon. For my second visit, I purchase the following:

Wide Shot,
Heavy Bomb.

Now Wide Shot is a bit weaker but is also cheaper than the price hiked 7 way and I can still complete the stage with a few seconds to spare. The heavy bomb is used to quick kill the boss.

But by the end of this stage I need to have at least $38,600. If I have $40,600 before SHOP in Stage 4 then I can buy all of the engine upgrades, 7 way and a fire bomb. If I don't then it is a reset. That's right some of my runs can end if I don't get lucky gold drops after defeating bosses.

Round 4: Dolimicca

Starting off with $41,650 and 2 seconds on Wide to spare, I destroy the first base and pick up a coin to spawn SHOP after losing Wide. If I lost Wide first in stage 4, the SHOP will not spawn after picking up a coin. If I lost Wide before stage 4, the SHOP will spawn ASAP.

$43,650 is not bad. It allows me to buy all of the gear I need and also 2 extra Fire Bombs. The big bonus is the quick exit trick thanks to my very low $ afterwards.

The purchase route is also important, by purchasing Turbo engine last; the game will select the most recent engine purchase. Turbo engine is used over the faster Rocket engine because it is easier to control, dodging projectiles is manageable and is still very fast.

After SHOP I use the first Fire Bomb to destroy the remaining bases. Because there is a fireball and a few dropped coins I ignored before the 6^th base it does a delayed boss spawn. It would have been awesome if I ignore base number 6, and collect the previous coins first and then destroy base 6.
Sadly going right next to the base and point blank shoot 7 way does not work and there is a risk that picking up too many coins may spawn the SHOP balloon.

Vs. U.S.B.M.G.S.TOT
One of the two SMS exclusive bosses, it replaced Crabumger because that boss is very processing heavy for the system.
Unfortunately the boss can be defeated in less than 2 seconds. It does make a System 16 style appearance in the 3DS version of the game with a lot more HP than the SMS version.

Round 5: Polaria

The first round to fully abuse infinite time 7 way. After destroying the second base, I use my second Fire Bomb to destroy the third base and the set of 6 M.F. by destroying those enemies and avoiding their coins I can destroy the remaining bases and quick spawn the next boss.

Vs Poppoos

A few notable tweaks in the SMS release, the time it takes from small to giant is way longer and the rate of fire from the giant is way less. But that doesn't mean the boss is easy to defeat as controlling Opa-opa with Turbo engine speed is a tad sensitive to movement. The other tweak is that the giant cannot be harmed until it reaches towards the destination spot which roughly takes 6 seconds after it first appears.

Round 6: Mockstar

Avoid picking up the first few coins from the bases and Asworm enemies. After that destroy the remaining bases, pick up those coins, it will be ok as you didn't pick up too many to spawn the SHOP balloon allowing the boss to spawn sooner.

Vs. DZ.DENO.ROMA

Just like U.S.B.M.G.S.TOT, the boss is exclusive to the SMS version as it replaces the processing heavy Winklone. Another easy boss as it requires point blank 7 way shooting. It does make a System 16 style appearance in the 3DS version of the game with a slightly different pattern as the weakspot can appear from either side making it less predictable.

Round 7: Pocarius

Feels notably easier than the previous two stages as all of the bases are placed on the upper half of the map meaning less tweaking on the Y co-ordinates. Again when killing the regular enemies, try to avoid picking up coins from those so you can stop the SHOP balloon from spawning.

Boss: IDA-2

According to the hints section of the US Manual it requires 64 twin shot hits to destroy it, even with turbo and 7 way it isn't possible to one cycle the boss. It might be possible in a TAS run or precise button presses to get consistent 7 way spreads instead of 5 or 4 way.

Round 8: Salfar

One final shop visit and I use my money buying on 9 Heavy Bombs. Technically you only need 3 but because I got turbo on, it doesn't hurt wasting a few frames just to make sure.

The first part of the round is a boss rush refighting against the first seven bosses.

Stunpalon – Open its mouth and bang it is dead
Volanda – As my bomb is set to Heavy I can't quick kill the boss as fast as the first visit.

Cobabeach, U.S.B.M.G.S.TOT, Poppoos, DZ.DENO.ROMA and IDA-2 are exactly the same.

Vs Leader of the Menons:

The final battle is a breeze with both 7 way and Heavy Bomb.
It sends out a small alien, each alien has 8 HP* more than the previous one.

The first four are quickly defeated with 7 way but the last two are notably different not only because of their HP but also their speed and direction.

Alien number 5 has 40 HP and immediately advances to the left, and then moves up or down depending on Opa-Opa's location. Once it has matched heights with Opa-Opa, it returns to the right, and then repeats the process. I use a Heavy Bomb to one hit kill this alien. I did this at the far left and not by the spawn spot is because of the rate of fire for this weapon isn't fast enough to quick kill the last two from the same spot.

Alien number 6 has 48 HP and simply seeks Opa-Opa out no matter where he goes on the screen. Pretty impossible to beat if you don't have a good engine and/or heavy bomb, it is THAT FAST. Because I kill alien 5 from the far left I have enough time to position Opa-opa and use my last Heavy Bomb to kill the last alien a few frames after gaining control.

Possible improvements:

Quick boss spawn for round 4:
What is hard about it? Trying to pick up coins before destroying the 6^th base and not spawning the SHOP balloon. At least two Fire Bombs will be needed for this stage IF it works.

Use Fire Bomb in round 7:
What is hard about it? The bases are on the upper half of the stage making it nearly possible, the tough part is figuring out the coins as it may end up being similar to Round 4 where it ends up delaying the boss spawn. That's right, quicker base kilsl doesn't always mean a quicker spawn if you don't know the most optimal coin pickups right afterwards.

Use Rocket engine:
What is hard about it? You move so fast that it is hard to dodge incoming enemies/projectiles on reaction also moving so far ahead to the left/right to find out you collide towards an enemy base. Literally blink and you are very likely going to screw up the run.

One cycle IDA-2
What is hard about it? Turbo 7 way and heavy bomb isn't enough to kill it.

Better strategies against both Alien 5 and 6
What is hard about it? Few seconds away from a fantastic run and you mess it up on the last three seconds. Maybe if I can kill number 5 on the middle of the map then go to the right and quick kill number 6 by using Heavy Bombs it might be possible.