Free spins are typically specific to slot games, but they are not necessarily available on all slot games. The particular games that free spins can be used on depends on the online casino and the specific bonus or promotion that awards the free spins.
Often, online casinos provide free spins for certain popular or featured slot games. For example, they may give free spins for a new game that they are promoting, or a popular game that many players enjoy.
However, some casinos do offer free spins bonuses that can be used on any of their slot games. In all cases, it's important to read the terms and conditions of any free spins offer to understand which games they can be used on and any other restrictions or requirements that may apply.
In some rare cases, certain bonuses might allow free play on other types of games, such as roulette or blackjack, but these are not typically referred to as "free spins" due to the nature of how these games are played.