Found out this game exists so I've been playing it through recently. Still doing the story mode and I got to the Prairie Entrance levels. Out of the all the levels I've played so far, these levels seem to be the most exploitable when it comes to out of bounds and such, and I found one today for the Gnoll Patrol mission in the first area (the second one is a boss).

Couple things to note:

• Since this is Source, you can gain speed by holding forward and rapidly pressing any of the directional keys. You can also gain speed by hugging walls.
• Spamming the shit out of dodge and heading in a direction can let you climb terrain. Note that it has to be between two things that can trick the game into thinking you're on proper ground, rather than messing with you and have you slide off. Shown at 0:50 in the video when I was first setting it up.
• Getting to max sprint and dealing with slopes is an interesting combination. 1:02 and above in the video showcases that, as you need max sprint to even be able to make that jump.
• I've only tested this with Miri currently. Other characters might act differently when it comes to this skip or maybe even more. I know Eira has a warping ability but it probably won't be useful for this skip specifically, and I have no idea if you can manipulate the warp position.
• Also Miri is kinda busted when it comes to her dodge and dealing with slopes. Her neutral move with right click (I have exactly zero idea what the move is called bare with me here) is good for getting up stuff, also shown in the video, but it is more in general.
• TL;DR funny source shit is finally useful in this game for a speedrun

If anyone has any questions I'd like to hear them. I don't really know where else to put this so here's just this random post in the forums. I also know the boards have literally nothing related to the story mode on them and is about the Ein Lacher battles and that's perfectly okay. I am eventually planning on running the whole story mode after I'm done with it and I route it properly.