Splinterlands nowadays is both pay-to-play and pay-to-earn too.
Pay-to-play with the Wild game mode (which was free-to-play in the past for years), and pay-to-earn with both game modes (Wild and Modern).
The rewards with the base card set are reduced, so the game is practically forcing (or at least trying to force) the players to invest money in Splinterlands (buy Splinterlands cards).