Neptune
First Stardroid in the route

Neptune - Sub Surface
The first few screens are on the top of a rising and falling sub. There are 2 helicopter enemies with 9 HP each, which is the focus of moving through this screen quickly. 
 The strats for this screen rely on being able to follow the rise and fall of the sub. You need to be able to move when the sub is at its bottom or peak of movement, and optimally more. 
 First Two Screens 
 Slide, bullet slide, bullet slide, and charge to get through the first screen. This should get you to the screen transition at the peak of the sub's movement. 
 Optimal Strat -  Jump through the screen transition and shoot on the other side. This connects with the chopper for 3 damage. Slide under it while charging and jump and hit it again. Avoid the missile shot while getting a third charge ready. 
 Alternate Strat  - Use Venus bubbles if you somehow have them. 
 Second Chopper 
 Use more bullet slides on the next Mets, then charge and get to the end of the screen. 
 With the sub being one tile lower here, you usually cannot jump and hit the chopper, except at the very top of the sub's movement at the very peak of Mega Man's jump. 
 Optimally you jump at the top of the sub and hit the screen transition at the top of Mega Man's jump, releasing the charge immediately to hit the chopper the first time. After that, just land the second 2 hits. 
 Four second slower  you can wait for the sub to be at its lowest, then trigger the screen transition. The sub continues bobbing up and down through the transition, letting you jump on the next screen at the peak of the sub's movement. This avoids the big jumpy enemy on the previous screen. 
 Alternate Strat  - Venus Bubbles also work here, if you somehow have it. 
 Last Sub Screen 
 Just get past the mets and jump through the transition.

Neptune Screen 6 - Inside Sub Room 1
Note, this is the check point 
 It is possible to take short hops and slide under the flying exploding enemy. There is no harm (other than time loss) in shooting it with a charge shot. 
 Similarly, there is no harm other than time loss in shooting the second floating enemy across the first pit. Due to lag from the explosion, it is faster to jump across the pit without destroying it. Note a full jump holding right will cause Mega Man to get bodied by the enemy and fall into the pit (by the running water if not directly) so be careful. 
 There is a full health drop on this screen. Grab it for damage boosts (and just to get it off the screen). 
 Note you want to use single lemons for the "Metool like" enemies here to not shoot the cracked pipes beyond them. On this screen it is only running water.

Neptune Screens 7, 8, and 9 - First Sub Damage Boost
Screen 7 
 This is a short screen with a single met, and a cracked pipe. This screen's presumed intent is to teach the player a charge shots or extra lemons will go through enemies and damage cracked pipes releasing potentially bad effects like the damaging steam jets. 
 Use specifically a single lemon to destroy the Met. Once you are near the ledge fire a lemon at the crack and jump over the passage down. You should release the steam jet and take 4 HP damage from it and fall through the screen transition in iframes. This lets you go through the first steam jet on screen 8 without being stopped by the flinching animation. 
 Screen 8 
   
 Screen 9 
 Use the damage boost from the end of screen 8 to slide past the steam jets while still in iframes. fall on the right side of the screen transition, and then start holding B to charge the buster for the next enemy (you will not charge until after the screen transition.

Neptune Screens 10, 11, 12, 13 - Pipe Jump
Screen 10 
 Fall into the water holding right and B. Destroy the first enemy. If you fell through the screen transition with no charge, this should be a half charge which will generate less lag - a full charge is otherwise fine. 
 proceed through this screen. 
 Pipe Jump 
 At the end there is a set of pipes you must slide through, with a steam jet on the floor beyond. It is fastest to slide through immediately, and make a frame perfect(?) jump on the other side to the ladder. 
 There is a 1 frame window to push jump before Mega Man falls out of the slide. Press A very late in the slide to jump. 
 Failure to jump loses a few seconds, but is still faster than waiting on the steam jet. You will take 4 from the steam, so in a race you might need to watch your health. 
 Slowest is waiting for the steam to go away and then attempting the jump, so failure will not take damage. There is no problem with waiting other than the time loss. 
 Screens 11 and 12 
 Both screens are climbing a long ladder with steam jets. Avoid the steam and continue. 
 The steam jets last for 10 puffs, or about 4 cycles of water splashing around the tank.  
 There is no harm in collecting the large drops other than the time required to collect them, and the fact magnet hand is the only way to get them without falling down the ladder. 
 Screen 13 
 Hold B to charge the buster through the screen transition. Jump and shoot the exploding enemy with the resulting full charge. When the hand clicks back onto Mega Man, jump across the room (the timing should align with the steam jets stopping). Slide and jump to the ladder.

Neptune Screen 14 - Last Long Screen
Water Section 
 You can jump against the wall above the slide-spikes, and fall to the floor without hitting the spikes. You can go that to neutral slide under them safely. 
 Jump through the water and shoot the enemies. You can collect the P-Chips to get them off the screen (amd to build towards your 30 if buying a W Tank). 
 Dry Section 
 Steam Jump 
 There is a floating enemy with a steam jet on the other side of the pit 
 Safe strat is to fire a full charge at the flier, wait for the arm to come back, then full jump once for timing purposes, then jump across the pit - the steam jet will stop 
 Faster strat  is ... 
 It is possible to land on the ledge and not get hit by the steam, then jump over it. This is not recommended since a death will send you back to screen 6. 
 The Rest 
 There is one more Met near a cracked pipe. Be careful with your lemons/charge shots to not trigger the steam. 
 Go through the boss gates without holding a charge for lag reduction purposes - you can hold B to charge the buster as Neptune spawns. (You can hold a full charge through the gates if you want, it just causes lag and loses time.)

Boss - Neptune
Damage Table 
 tbd 
 
 
 
 attack 
 Damage 
 
 
 Neptune Contact Damage 
 
 
 
 Salt Water (large) 
 
 
 
 Salt Water (drop) 
 
 
 
 Ceiling droplet 
 
 
 
 
 Attack Pattern 
 Neptune will take several hops towards the player, mixing both jumps or low jumps. You can slide under them. It is recommended you stay close to Neptune after going under him. 
 At some point after you slide under them, Neptune will stop jumping and attack. The attack used depends on how far away Mega Man is. 
 Far attack - Neptune jumps up and down in place and makes damaging water fall from the ceiling. This is EXTREMELY LAGGY! This is why you should stay close to Neptune. 
 Close attack - Neptune lobs a salt water at you, which splashes and breaks into 3 smaller (still damaging) droplets. 
 Main Stage Fight 
 For new runners, it is very likely you will be here with very few HP after all the damage boosts in the stage. You may want to get comfortable executing this fight damageless. 
 You cannot through normal means have the weakness here, so use buster. 
 Hold B to charge a full shot to open the fight. After the first hit, use half charges for DPS, though hitting with a full charge is fine if it happens. It takes one full charge and 8 half charges to do the 19 HP damage to Neptune. 
 Stay close to Neptune to avoid the long laggy attack described above. When Neptune uses salt water, you have a few options to avoid the attack. 
 
 Jump and wiggle over Neptune, then land back in front of him 
 Slide away, then slide close again going under the salt water lob 
 Slide away to avoid the attack and accept some time loss. 
 
 Slide under Neptune's first jump after an attack. Note Neptune may stop after only 1 jump, so always be ready. 
 Refight 
 Neptune's weakness is Spark Chaser (from Earth/Terra) 
 Since this is a homing weapon, fire it and then avoid Neptune, staying close enough to avoid the laggy attack. 
 You may also want to not stand as close as possible to Neptune when he is in a corner - the Spark Chaser may despawn off screen rather than bouncing back into Neptune. (Though maybe this is faster?)