A couple of email conversations with the recruiter, then a talk with a couple of engineers, including informal questions about C++ language, code design, computer architecture, operating systems (some of these questions became deeper and deeper, requesting very specific details), and a couple of code solving problems on a shared editor. Finally, a conversation with a manager, basically centered on soft skills and for talking about the results of the process.

Four engineers, technical manager, and group manager, took about 6 hours total. Engineers were free to ask any questions they liked, so difficulty was variable. From completely non-technical, to easy, to somewhat difficult technical questions were asked. Took me to lunch, was good to get to know the culture and personalities.