ADL stands for "Adventure Development Language". It was created by Ken Williams for the first games created by Sierra (then known as On-Line Systems), the company that he founded with his wife, Roberta Williams.
The games using this engine were known as the Hi-Res Adventure series.
Several of them were included in SCI game collections (the "Roberta Williams Anthology" and "King's Quest Collection Series").
Games using this engine
Japanese names for those games: