The Boot Sector Games book series
After introducing the 8086 instruction set and Assembly, Programming Boot Sector Games describes the source code of several games each of which fits into the boot sector of a PC, 512 bytes. The sequel, More Boot Sector Games, covers more games.
The introduction to 8086 insructions in the first book is short and to the point. It's enough to code fairly advanced programs without overwhelming with information as processor manuals and full length books typically do. But Oscar also shares his considerable experience and insight by discussing many 8086 tricks, idioms, practical advice, and optimization techniques.
The books cover not only games but also other interesting 8086 programs such as a BASIC interpreter and a tiny operating system.
Since some of the code is dense and advanced, reading it once may not be enough for a full understanding. But a great feature of these programs is they fit into 512 bytes, so there's an upper bound to complexity which rereading the code and the text helps overcome.
The only downside of the books is they are password-protected PDF files. It's an annoyance when opening them in ereading apps but is easy to overcome.