Continuing the detective work for the missing player model:
* Removing player.mdl (and in turn, using the default player.mdl) didn't do anything - still no player.
* I tried loading up HQ1 in regular Steam Half-Life, and lo and behold:
If you can see it (it's really dark), there's the player model - but it's Gordon Freeman, not my player.mdl (which is in fact the robot marine model from the German HL version). So... something's definitely going on here with the Steam version of HL.
* I looked into trying SoHL 1.9, but... different versions of Spirit of Half-Life usually introduce a whole host of new bugs, and even may leave out features. That's because it's usually made by different people nowadays. I read some comments about 1.9 and they weren't pretty, so I discarded that thought.
* I looked into the Locus system because I remembered, you could even make it so the player was able to pick up objects. I loaded player.mdl into the game with an env_model (and that worked fine, so it's not the model's fault either), and used motion_manager and calc_position for the *player to move the model along with the player (see video).
It looks super funny. But might work as a workaround xD The part "jump and run" was never really about it looking perfectly fine anyway. And for the intro, I'll just used a static env_model the camera hovers around.
Oh yeah, the motion_manager has to be triggered a few times every few milliseconds because upon reloading the model doesn't follow the player anymore. That's something I have to be mindful of.
The next thing I noticed was, the game_text was not displayed in camera view. Not even env_messages, including the text "Saved..." that should be displayed when hitting F6. It only gets displayed when not in camera mode. I'm going to have to research what's up with that.
Although I've found a cool side-effect of using env_message: In theory I could provide translation by offering titles.txt of different languages. But that's a thought for later on.
And I've also noticed that the camera does NOT reset after loading anymore. In both "jump and run" parts you could just quicksave and quickload to get out of the 3rd-person view. That's no longer possible, and I attribute that to SoHL1.8.
Interestingly, fixing the camera was solved by triggering it with a multi_manager instead of a func_button. It probably has something to do with who triggers it...
So anyway, I'll look into what's causing the missing text, add the quick fix for the player model in "jump and run" and then carry on with HQA maps.