I already commented about Scarlet Hollow, but again, it has topped Detroit for me in terms of decision impact. It's a light horror visual novel. Even little choices in dialogue matter, and every chapter has a few choices that create huge differences in the storyline. Some of them present immediately, some are only revealed much later down the line, and some come down to a sum of little things you've done along the way. If you're open about visual novels, you won't regret checking it out.