Back in the 90's many players not only played it on the keyboard, but they played pirated copies as well, so no manuals.
I remember as a kid seeing the copy protection screen and not understanding even that it was a copy protection. My copy was French even, and I had zero French knowledge. But... so it goes with PC games at the time: we start exploring controls using the typical "action buttons" such as Space, Enter, Left Shift, Alt and Ctrl (thanks to Keen). Another World was super easy to figure out, as it played entirely with just one button (Enter) and the arrow keys.
It's not a very difficult game either. I remember we finished it very quickly. It had some annoying levels like rolling in the ducts, and the big water pool puzzle. Most other levels just go very smoothly.
Turbo XT 12MHz, 8-bit VGA, Dual 360K drives
Intel 386 DX-33, Speedstar 24X, SB 1.5, 1x CD
Intel 486 DX2-66, CL5428 VLB, SBPro 2, 2x CD
Intel Pentium 90, Matrox Millenium 2, SB16, 4x CD
HP Z400, Xeon 3.46GHz, YMF-744, Voodoo3, RTX2080Ti