Recently, I posted pychess.org as a great place to play many different chess variants.  But I have also found some other great sites, as recently as today:

• pychess.org
• lichess.org for live chess
• lidraughts.org for live checkers and variants
• lishogi.org for full board shogi (no variants yet, beta version)
• online-go.com is the go to site for go (OGS)
• xiangqi.com for Chinese Chess

For more turn based games similar to littlegolem, there is also yourturnmyturn.com

Anyone know any other good sites to play strategy games?

itsyourturn.com has an interesting Reversi variant called Hexversi that I like to play, as well as some good chess variants like Dark Chess.

Goldtoken.com has many game types with variants , tournaments, ladders, free or various levels of paid membership

Brainking.com has lots of chess variants

BoardGameArena has quite a number of pure strategy games now (50+), and it fully supports turn-based play, as well as real-time ones. There’s a list of all the relevant games in this group here:

https://boardgamearena.com/group?id=6701427&section=publicinfos

iggamecenter.com is one of my favorites!

PlayOK is great for live card and abstract board games. It runs in HTML5 and has a fairly large user base for games like Xiangqi, Makruk, Backgammon, and Canasta, particularly if you're on at certain times (it's almost noon in Thailand right now and Makruk has 900+ players live)

https://www.playok.com/

The best abstract board games selection is
probably at MindSports.nl