Some time back after downloading a ROM of this game I was talking to Mike on MSN about some improvements to his Hard Corps runs. I dunno whether he's still planning on improving them at some point, but I figured I should post my findings here in case anyone else wants to give it a shot (are frezy_man or any of the other Contra runners interested in this game?). All the points I make are for a Browny run - Browny is probably still the best character for an unassisted speedrun.
* Firstly, the trick used in adelikat's TAS of sliding off ledges and keeping your slide speed can be used in unassisted play. All you have to do is do a slide at the edge of a ledge and release the left or right button before you leave the ledge, and you'll keep your slide speed in the air (but won't be invulnerable like when sliding along the ground). Probably several places this is usable, see the TAS for ideas.
* On the flamethrower spider miniboss on level 1, if you position yourself just to the right of him in the centre of the screen, his flamethrower will go right over Browny's head. Standing here and killing him either with the A weapon or with D weapon spam is faster than killing him from the right side of the screen like Mike did in his old run.
* On the Lab path, you can kill the jetpack guy's first form with a single Yoyo shot by firing it diagonally up and right from the right spot so it ends up above him just as he becomes targettable; it should then drop down towards him and basically follow him around his path and kill him in a fraction of a second. (Mike tried this at the marathon but didn't quite kill him with the first shot).
* On the Lab path, after landing, when you have to destroy the wall of the Lab, using the B weapon is actually about half a second faster than using the Yoyo (yes, really). The trick is to make a couple of slides, then start holding down fire and jumping up and down to flood the screen with B weapon projectiles. Because the wall is so big, as soon as it comes into range, basically all the projectiles you've fired will hit it at once and destroy it almost instantly, before you even get into yoyo-spamming range.
* On the Lab path, if you grabbed the D weapon either on level 1 or when the lab path ship crashed, you can slide your way through the lab section with the randomly spawning soldiers without having to fire a shot by just holding down fire before you start sliding and keeping it held; the D weapon balls orbitting you will kill any of the randomly-spawning enemies before they get close. The grenadier won't be killed by one ball, however, so you need to stop sliding momentarily before him to make sure you slide through him, or learn the right spot to start sliding from if you just want to be able to spam slide through the whole room.
* Something I only just discovered literally midway through writing this post; the Lab boss can be killed much faster than in Mike's old runs by getting the Yoyo to stop over its head. The trick is to fire it up at just the right moment so that the moment it would normally change directions and return to Browny (i.e. the moment its velocity is at or near zero) coincides with the head becoming damagable (and targettable). Then it will remain stationary over the boss's head and the boss will die several seconds earlier than it does in Mike's runs. The timing is sufficiently forgiving that by using the boss music as a cue, you should be able to get it consistently in unassisted play (that's how I just did it). Credit for this technique goes to Gigafrost - I got the idea from his post on page 5 of this thread.
* On Stage 3, jumping over the cars is obviously faster than destroying them, though it takes some experimenting to find a way of doing so consistently.
* On Stage 3, using the A weapon to destroy the doors before the final boss seems to be a fair bit faster.
* One possible use of a bomb is for killing the giant flies that come out of the stone head on Stage 4. If you jump above the head and use a bomb right when the first set of 4 flies comes out, the instant damage will kill the first wave of flies and the shockwave will take out the second wave the instant they spawn.
* Ooh, another mid-post find. On Stage 4, you can also quite easily use the 'stationary Yoyo' technique on the boss on the bridge in unassisted play. Watch Gigafrost's obsolete TAS to see the method in action. The music doesn't change for this boss but you can time the shot correctly fairly reliably by watching the position of the boss's hands. I'm really happy that this is possible unassisted because that boss is one of the uglier and more fiddly ones using the method of Mike's old runs.
* One possible faster method than Mike's of dealing with the final Stage 4 boss is to position yourself below the boss, just to the right of the centre, and spam Yoyo up at it at just the right pace to always knock the boss back to the left of the screen. Then, just when the lightning beam is about to be pointing vertically downwards, slide left through it, then return to the same position under the boss and resume spamming. This allows much less disrupted attacking of the boss than constantly circling it like Mike does in the old run. I'm not sure how reliably you can survive it though, I didn't test it much. Edit: Forget this - the people above who suggested using the B weapon back in 2006 are right, it kills this boss much faster than the yoyo for some reason.
* If taking the 'fight' path, it may be useful to not immediately kill the fourth mutant the doctor creates. You can let it live for a few seconds without losing any time, since the doctor won't start creating the next mutant until the doors close anyway, and it throws out random weapons, including extra bombs. If an extra bomb would be useful, you should let the mutant throw out the first three weapons before killing it (that's how many it gets through before the doors close). Again, I think Mike did this in the marathon.
* The final mutant always jumps to the left of the screen when it becomes vulnerable, but the direction it slides during its initial invulnerable sliding attack (and consequently what side of the screen it ends up on when that attack ends) depends upon whether you are stood to the left or the right of it. If you stand to the right of when it starts its sliding attack, it will finish its slide at the right of the screen and jump from there, which means you can position yourself underneath where its vulnerable form will land before it jumps, which means you won't need to slide through its leg before attacking it like Mike does in his old runs. That said, a careful slide from the right spot during its jump could probably acheive the same goal even if you let it slide to the left.
* On Stage 5 of the Lab-Fight path, the boss with the spiked tail that jumps in and out of the water can potentially be killed a fair bit quicker with the Yoyo. Using a bomb (e.g. one obtained from the weapon distributor mutant) can also be very effective here.
* The start of Stage 5 on the Chase-Surrender path can be done faster using the D weapon. Just keep spamming it as you run and you'll never have to turn around to shoot anyone. I think this featured in the marathon too.
Hopefully if I've forgotten anything we discussed, Mike will be able to fill the gap.
I would love to try and beat the runs myself, but I don't have the game, a Genesis/Megadrive, or an NTSC TV.
* Firstly, the trick used in adelikat's TAS of sliding off ledges and keeping your slide speed can be used in unassisted play. All you have to do is do a slide at the edge of a ledge and release the left or right button before you leave the ledge, and you'll keep your slide speed in the air (but won't be invulnerable like when sliding along the ground). Probably several places this is usable, see the TAS for ideas.
* On the flamethrower spider miniboss on level 1, if you position yourself just to the right of him in the centre of the screen, his flamethrower will go right over Browny's head. Standing here and killing him either with the A weapon or with D weapon spam is faster than killing him from the right side of the screen like Mike did in his old run.
* On the Lab path, you can kill the jetpack guy's first form with a single Yoyo shot by firing it diagonally up and right from the right spot so it ends up above him just as he becomes targettable; it should then drop down towards him and basically follow him around his path and kill him in a fraction of a second. (Mike tried this at the marathon but didn't quite kill him with the first shot).
* On the Lab path, after landing, when you have to destroy the wall of the Lab, using the B weapon is actually about half a second faster than using the Yoyo (yes, really). The trick is to make a couple of slides, then start holding down fire and jumping up and down to flood the screen with B weapon projectiles. Because the wall is so big, as soon as it comes into range, basically all the projectiles you've fired will hit it at once and destroy it almost instantly, before you even get into yoyo-spamming range.
* On the Lab path, if you grabbed the D weapon either on level 1 or when the lab path ship crashed, you can slide your way through the lab section with the randomly spawning soldiers without having to fire a shot by just holding down fire before you start sliding and keeping it held; the D weapon balls orbitting you will kill any of the randomly-spawning enemies before they get close. The grenadier won't be killed by one ball, however, so you need to stop sliding momentarily before him to make sure you slide through him, or learn the right spot to start sliding from if you just want to be able to spam slide through the whole room.
* Something I only just discovered literally midway through writing this post; the Lab boss can be killed much faster than in Mike's old runs by getting the Yoyo to stop over its head. The trick is to fire it up at just the right moment so that the moment it would normally change directions and return to Browny (i.e. the moment its velocity is at or near zero) coincides with the head becoming damagable (and targettable). Then it will remain stationary over the boss's head and the boss will die several seconds earlier than it does in Mike's runs. The timing is sufficiently forgiving that by using the boss music as a cue, you should be able to get it consistently in unassisted play (that's how I just did it). Credit for this technique goes to Gigafrost - I got the idea from his post on page 5 of this thread.
* On Stage 3, jumping over the cars is obviously faster than destroying them, though it takes some experimenting to find a way of doing so consistently.
* On Stage 3, using the A weapon to destroy the doors before the final boss seems to be a fair bit faster.
* One possible use of a bomb is for killing the giant flies that come out of the stone head on Stage 4. If you jump above the head and use a bomb right when the first set of 4 flies comes out, the instant damage will kill the first wave of flies and the shockwave will take out the second wave the instant they spawn.
* Ooh, another mid-post find. On Stage 4, you can also quite easily use the 'stationary Yoyo' technique on the boss on the bridge in unassisted play. Watch Gigafrost's obsolete TAS to see the method in action. The music doesn't change for this boss but you can time the shot correctly fairly reliably by watching the position of the boss's hands. I'm really happy that this is possible unassisted because that boss is one of the uglier and more fiddly ones using the method of Mike's old runs.
* If taking the 'fight' path, it may be useful to not immediately kill the fourth mutant the doctor creates. You can let it live for a few seconds without losing any time, since the doctor won't start creating the next mutant until the doors close anyway, and it throws out random weapons, including extra bombs. If an extra bomb would be useful, you should let the mutant throw out the first three weapons before killing it (that's how many it gets through before the doors close). Again, I think Mike did this in the marathon.
* The final mutant always jumps to the left of the screen when it becomes vulnerable, but the direction it slides during its initial invulnerable sliding attack (and consequently what side of the screen it ends up on when that attack ends) depends upon whether you are stood to the left or the right of it. If you stand to the right of when it starts its sliding attack, it will finish its slide at the right of the screen and jump from there, which means you can position yourself underneath where its vulnerable form will land before it jumps, which means you won't need to slide through its leg before attacking it like Mike does in his old runs. That said, a careful slide from the right spot during its jump could probably acheive the same goal even if you let it slide to the left.
* On Stage 5 of the Lab-Fight path, the boss with the spiked tail that jumps in and out of the water can potentially be killed a fair bit quicker with the Yoyo. Using a bomb (e.g. one obtained from the weapon distributor mutant) can also be very effective here.
* The start of Stage 5 on the Chase-Surrender path can be done faster using the D weapon. Just keep spamming it as you run and you'll never have to turn around to shoot anyone. I think this featured in the marathon too.
Hopefully if I've forgotten anything we discussed, Mike will be able to fill the gap.
I would love to try and beat the runs myself, but I don't have the game, a Genesis/Megadrive, or an NTSC TV.