Being able to kill Osana early with some cheeky actions is hardly a failure of game design, if anything, these sorts of systems inevitably have these cases, and finding them to the players enjoyment should be encouraged, not discouraged.
Alex's real failure is this shit
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Rather than feeding the player clues, hints, maybe a first rival tutorial, you just buy a strategy guide in game. Its like he's never played a hitman level without the wiki open, and decided that it should be an integral feature. Then, rather than having to lampshade, hint at, and provide in game clues and guidance to the actions, you just have to go perv out on some stairs and do the provided busywork. That, is stupid fucking design. Making the currency pantyshots is just the icing on the stupid cake.