Comment # 6 on bug 1000498 from Stefan Hundhammer

I didn't find any clearly specified system requirements for Tumbleweed, but for
SLE-12 (which is very much the same code base), here the minimum specs are 512
MB RAM:

https://www.suse.com/de-de/products/server/technical-information

Leap has even stricter requirements: 1 GB RAM

https://en.opensuse.org/Hardware_requirements

You might get lucky with 256 MB if you try a text-based (ncurses) installation
and avoid the detailed software selection and probably also the expert
partitioner, but that amount of memory is clearly out of spec these days.

Please notice that it's very difficult to come up with a useful error message
in that case since things will fail in mysterious ways if we run out of memory:
Creating objects in Ruby or C++ might fail, maybe external programs (parted,
modprobe) fail. This is not good - we know that. But the only alternative 
would be to get back to the hard check for available memory and to refuse to
even start the installation, which OTOH would mean that you don't have a chance
to even try a low-profile installation like described above (text only, no
fancy things).