Although the card does not say "target", do spells such as Alchemist's Gambit target you, the caster? The presumption is, of course, that you are wanting to take an extra turn, even at the cost of potentially losing the game at the beginning of that turn's end step, and so you would want to target yourself but it doesn't *say* "target".
115.10. Spells and abilities can affect objects and players they don’t target. In general, those objects and
players aren’t chosen until the spell or ability resolves. See rule 608, “Resolving Spells and
Abilities.”
115.10a Just because an object or player is being affected by a spell or ability doesn’t make that
object or player a target of that spell or ability. Unless that object or player is identified by the
word “target” in the text of that spell or ability, or the rule for that keyword ability, it’s not a
target.
Therefore, it doesn't target.