NSW stepdad 'abused girl as she slept'

A man who sexually assaulted his stepdaughter over years says he played a "game" to see how many sex acts he could commit on the sleeping girl before she would wake up.

The man, who cannot be named for legal reasons, told a Downing Centre District Court he thinks the girl started having a crush on him as she started becoming a "woman" around the age of 12.

He said he started filming her sleeping after telling her, "I could do anything I wanted to you while you were asleep".

He says the girl, then responded, "do it".

"So you thought you would perpetrate all these actions on her and then show her the next morning?" Judge Paul Conlon asked on Tuesday.

"I don't condone (the actions)," the stepfather, who is self-represented, said.

The man has already pleaded guilty to 99 counts relating to the girl's sexual abuse but is on trial for allegedly drugging her and her mother.

He said the girl would sometimes sleep after coming home from school so they could have "our time" later in the night.

Without a lawyer, another person has to ask him prepared questions during his testimony.

He said the girl would have known that he was performing sex acts on her as she slept after the first time he showed her a video.

"Eventually it then became a game of how far you could go without (the girl) waking up?" the questioner asked.

"Unfortunately, yes," the stepfather replied.

Judge Conlon at times had stern words for the stepfather, saying many of his claims had not been brought up when the girl or her mother gave evidence.

The man has previously told the jury that he and his stepdaughter acted like a "married couple" from 2009 to 2014.

He testified the girl's mother said "at least she's legal for you now", when the girl turned 16.

The mother physically and verbally assaulted him during their marriage, he said.

The trial continues.