Starcraft – How to change the game speed during a match in Starcraft 2 (SC2)

• Most of the advice to stop Nydus worms applies in general. First of all, you should be keeping an eye on your base no matter which race you are facing, and regardless of whether or not you have scouted a Nydus Network in the Zerg's base. All races have ways of getting units into the back of your base without going up the ramp. Medivacs, proxy pylons, overlords with ventral sacs, warp prisms, blink stalkers, colossi, reapers, etc, not to mention pretty much any air unit.

• Denying vision to the zerg player by harassing overlords should be done in general, not just to stop worms.

• To help detect the nydus worm (and all other threats mentioned in previous bullet), spread buildings out in your base, so you have vision everywhere. Terrans can spread supply depots, protoss have pylons, and zerg have creep tumours, or overlords to spread around.

• Learn the sound a nydus worm makes when it completes. Sadly for us zerg players, the nydus worm announces itself to all players with a loud scream, similar to how everyone hears "nuke launch detected". On the plus side (for us), it only screams as it is finishing. This won't help you stop the worm, but it will alert you that you should be looking for the worm to make sure it's not in your base, or if it is, mobilize some troops to defend.

• In team games, consider using the team colors option for the minimap, so your units are green and your opponents are red. This will make the nydus worm stand out in your minimap more than if you are orange and your opponent is yellow, or some other combo of similar colors.

• Worms don't have a lot of HP, even when they complete. When they are building, a handful of units can kill it before it completes. I just did a quick test; 3 marines starting to shoot as soon as the worm reaches 50% done can kill it just after it finishes, enough time for only a few units to get out.

• Remember that each worm costs the zerg player 100 minerals and 100 precious gas. Each time you kill one before it completes, the zerg is behind on resources. They can also only be building one at a time. (specifically, one per Nydus Network)

I also agree this is a poor approach, but since you piqued my curiosity, I went and installed wireshark.

Here is an average SC2 packet:

User Datagram Protocal, Src Port: 50542, Dst Port: bnetgame (1119)
Length: 32
Data (24 bytes)
Data: 76ed0100077ce965cd7e4018cc8040001e92508e0fa0cd00

I remember that the original Starcraft had the option of using the IPX protocol as an alternative to TCP, so I guess I shouldn't be surprised that they rolled their own protocal for Starcraft 2. What's more the average packet size in my sample was 60bytes, which with overhead means you're getting 24 bytes of data. Without a good insight in to how they do sequencing, any sort of parallel data being transmitted on that connection is going to be hard to reassemble.

At this point they don't even need encryption, their chopping scheme for transmitting smaller packets will act as obfuscation.

Since efficient network transfer of data is a bit of a hobby of mine, I decided to dig deeper.

Storm UDP Protocol
This protocol is defined and processed by functions within Storm.dll and is used for numerous games - namely, Diablo 1, Warcraft II: BNE, Starcraft, and Starcraft: Brood War.
(WORD)      Checksum
(WORD)      Header Length
(WORD)      Seq1
(WORD)      Seq2
(BYTE)      CLS
(BYTE)      Command
(BYTE)      PlayerID
(BYTE)      Resend

I take back my original assessment, you can definitely identify the sequence pretty easily. What's more It looks like you can break apart the messages fairly easily. The concern then becomes extracting information from the 4-8 Bytes of data in the messages.

So let's look at that data.

== 0x36 - Stim Pack ==
{{{
  // No parameters.
}}}
CLASS 2

----------------------------------------------------
== 0x35 - Zerg Bldg Morph ==
{{{
    WORD wUnitType;
}}}
CLASS 2

Fascinating. Apparently SC2 is transmitting the same codes you find in a replay over the BattleNet. So breaking apart a replay is the same as using a packet capture. Your only real decision should then become: Do you need the data in real time? If you don't then using replays will be easier than disassembling the data from tshark.