Thanks for the moral support.
I'm a bit perplexed, frankly. It looked like one, except that it was far too big. German roaches (don't blame me, that's the actual name) get up to 1.6 cm, I've learned. And it did not look like an American one, which get bigger apparently. That critter was about 4cm. I examined it diligently before throwing it out, but I'm no expert.
Oh well, no way around it but to turn the entire flat upside down and vacuum everything. And worst of all, get those stacks of paper sorted. As if I had nothing else do to.
I would very much prefer a mouse. I like mice. Or a rat, I like rats, too. Do rats eat roaches? I know that tarantulas do, but I'm not having one of those in my place. Same goes for wasps and hornets. Perhaps I should buy a rat and house-train it.