I will try to go through various point step by step. Note that this post is only about the arcade version and the MD version (and not about the other versions).
Jeneki wrote:
Sengoku Strider wrote:
But is this a rank-based game?
The arcade version, yes is very rank-based on the P powerups and quite noticeable after the first two.
I agree.
Here is some context to the post. I got the 1CC on the original MD version (normal difficulty) well over a decade ago. Then few years later I tried the arcade version. I practiced it for a while but then moved over and then didn't play it again.
Couple of years ago I started the arcade version again. I posted a clear in the hi score section
[it was a 1-miss clear with the miss being on stage-5
]. Note that the score I posted on the hi-score board was a 2-miss clear (on stage-4 and stage-5). That was my second clear of the game immediately after getting the first one. The game instantly becomes easy once you lose a life (and then starts picking up on difficulty again gradually). Also, past a certain point, the arcade version also seems to give quite a few extra lives.
Then I saw another video posted by some other player in the same thread and I noticed a noticeable difference in difficulty. It was something similar to what you mentioned. It seems that the base weapon strength wasn't upgraded much.
Apparently, my impression is that the rank in ARC version seems to depend on two things. However, I don't know much about the details. The two biggest factors seems to be:
(i) How long you are going with a no-miss.
(ii) Power-level of main shot.
Personally, I find it more fun to play the arcade version without manipulating power-level. Also, I don't seem to re-call any rank on MD version (to any significant extent at least). So keeping power-level down won't work there I think.
===================================
===================================
Now I will try to cover some other points. Regarding the "secondary weapon", here is my ranking of them. Once again this applies to arcade version and MD version:
(i) Side-pods
Easily the best. Also, on stage-4 and stage-5 they are very useful (unless the rank is really low on ARC version).
(ii) Red and Green guided missiles
Both are decent. Certainly don't seem to be as good as pods though. Red missiles seem to have more "power". On the other hand, the green missiles seem to be more "guided".
(iii) Rotating turret
Pretty powerful. However, due to the slow rotation and low frequency of fire, it isn't as good as the above two weapons.
(iv) Six-Way shot
Weakest secondary weapon.
===================================
===================================
Regarding the ARC and MD versions, there are number of differences. As mentioned before, one difference is rank in arcade version (which seems to be absent or minimal in MD version). The second difference that I noticed is that boss battles for stage-4 and stage-6 seem to have some differences in both ARC and MD versions. Personally I find the stage-4 boss battle to be somewhat unfair in both versions.
It is also worth mentioning the hardest difficulty setting in the MD version is a fun challenge if you have already got a 1CC on normal.
===================================
===================================
Finally, some discussion about "free movement" in stage-4 and stage-5. In both ARC and MD version, if I am not re-calling incorrectly, once your ship takes a certain direction
[left, right, up, down or some diagonal direction
], then it doesn't seem to stop unless you press a direction button again.
One simple tip is that, generally speaking, I keep holding the left button just press up and down button to dodge attacks. However, note that this only works if you can afford to stay on the far-left of the screen. There are good number of points where this doesn't apply. For example, towards the last section of stage-4, I usually try to avoid moving up/down and just move left/right as much as possible (while trying to stay close to the floor).