Website to practise thematic games [blitz]? As stated in the title, are there any websites out there to play thematic games in Blitz (or quick time control) ? The idea is to practise a specific opening, starting from a precise position (arising after the exchange Grünfeld for example). I know a french website where it's possible but for corresponding games only.
Thanks in advance.
Lichess has what you are looking for:



But you may have to check out when a specific opening theme may be scheduled in their tournament table. Also Lichess has a feature to start your own thematic tournament at any time of the day, but attracting players to the custom tournaments typically does not work.