Although even if you focus on old slots, you will not always be able to get, as many gaming content providers have long started to translate games to a new format. It all started with the most popular games, and the rest followed. The moment when browsers will no longer support flash very close, so all games that have for developers some value should be translated into HTML5.
Without running the slot, you will not recognize in the flash, it is completed or not, because nowhere is this marking. So, in your quest you will need to act at random. As mentioned above, new items can immediately. Due to the fact that soon browsers will stop supporting the Flash player, the developers of slot machines make no sense to create such games.
Is there a difference in the slots of Flash and HTML5?
If we talk about cases when the game is translated from the old format to a new one, then there should be no difference. Although sometimes it happened that the players doubted the accuracy of the new version. For example, after in 2018 released HTML5 version Dead or Alive, Some players with experience began to say that they noticed changes in dispersion. In their opinion, a high dispersion for which this slot and loved, became noticeably lower. However, NETENT officially denies it.
In fact, there may be minor changes in the games – a little different graphics or effects, however, mathematics remains unchanged. It means RTP and dispersion do not change. In case of changes in mathematics, the developer would have to re-licen the game. Also note that for different jurisdictions, developers can have different versions of one game and all these versions can be with different RTPs.
If we consider generally, it is considered that HTML5 games are less problematic. Plus, this format gives developers more opportunities, so there is a chance to create more spectacular slots.