Some games where an opponent resigns early I'd like the ability to continue the game as a casual vs. computer game in order to practice my endgame skills. It would be great if there was a button "take over computer level X from this position for color Y" feature, allowing me to soldier on.
You can go to the analysis board of a game, and select the move on the move list where you want to start, then click the hamburger menu button under the move list and choose "Continue from here".
Already exists. Go to the Analysis board when the game is finished, click the three lines menu icon below the move list, and click 'Continue from here'. All games vs the computer are casual. You can even continue against a human player if you want.
Wow, awesome! Thanks everyone. Lichess is amazing.