Before I played Spec Ops: The Line, I was staunchly against suicide in all instances.

The ending puts you in a situation where you’ve more or less committed genocide (or at least horrifying war crimes), for ultimately no real cause. There’s no solution to make amends, you can’t undo what you’ve done.
It then puts you in a position where you can effectively choose to commit suicide.

If given the choice, most people would go back in time and kill hitler. But what if you WERE hitler, and suddenly realized the true implications of your actions. You were responsible for the torture and murder of millions on innocent people, actions that are impossible to forgive. Would the moral and ethical action be to kill yourself? Even if doing so wouldn’t prevent further death or harm to others?

That ending made me rethink my stance on suicide, the topic is far more complicated than I used to think it was. To this day, every now and again, I still think about the choice at that ending.