Overtime Question

What happens in the CFL overtime if the defense returns an INT or fumble for a touchdown?

Is the game over? Does a defensive touchdown count?

SECTION 8 – TIE GAME
In the event that the score is tied at the end of the second half of a game, each team
will be given the opportunity to score using the following procedure:
• The first team, as determined by coin toss, shall scrimmage the ball at the
opponent’s 35-yard line and may advance by consecutive series of downs until it
makes a score or loses possession.
• The second team will then scrimmage at the same 35-yard line and proceed as
above.
• If the score is still tied, the procedure shall be repeated at the opposite end of the
stadium.

Yes.
Although I don't think its ever happened yet.

im not so sure im reading the rules that say its a loss a possession and the team gets the ball on the 35. i think once the INT happens it just ends that teams attempt and allows the team that just INT it to go for the td on offense. im pretty sure thats how it goes in the NCAA but i could be wrong

Touchdown by the defense game over I think

on a interception, fumble recovery,blocked fg and ran in for a td by the defense the game would be over, unless the team that did 2 of the above already scored a td on their possesion they would just down the ball and win the game

While I agree with Jakob7's interpretation of the Rule Book, CFL Football Operations confirms RevClark is right. Here's their response to the question:

"It is a live ball if there is a turnover in overtime. If the defensive
team scores a touchdown, the game is over, regardless who started with
the ball."

Taking it a step further, although not confirmed by the league, I presume the defensive team on a turnover play could also end the game by, on the run, kicking a single or drop-kicking a field goal.