The Re-Connect Tab's Play a Chess Engine button allows offline play which can be used when connected too but play is offline.
When Play a Chess Engine is selected the Pulsar Chess Engine view will appear over the Re-Connect tab. Click/tap in top right Re-Connect to remove this view.
Click or Tap in Pulsar view top left, the game button for a menu with new game to configure the game type. In the new game view that appears over Pulsar board, difficulty and variant like Chess, or shuffle chess(Chess960), or crazyhouse can be chosen.