in 5e shadowdancer is kind of a sub class of monks. no rogue-ish subclass of this type, though
Better yet, give us tools so we can implement *any* class ourselves
In 5e there is no 'hide-in-plain-sight' like the 3.x version. (though the ability exists it is a ranger ability and nothing like Shadow Dancer). Instead, the Rogue has a mechanic whereby they can always use a bonus action after they act in a round. If they are close enough to anything that gives them enough cover they can use the bonus action to then hide. So you can launch your sneak attack, move to cover and bonus action hide in the same round provided the environment allows for it. Shorties have the advantage of being able to use larger party members to provide adequate cover in order to use the hide bonus action as well.
The Way of Shadows Monk, aka Shadowdancer/Ninja, is really cool. They get an at will teleport via shadows, gets minor illusion cantrip, can cast some Illusion spells via Ki, and can turn invisible, plus all the regular cool stuff monks do like walk on walls and flurry of blows.