Arcade Trial no free game?

I just started wondering into Apple Arcade and got myself a month of free trial. Upon signing up, it advertised as “no ads, no in-app purchase, free game”, but when I tried to play certain games, it says to buy the full game. This has happened to at least two games which I downloaded. I haven’t seen an entirely full game that is free. Is this right? Then what am I paying for? Just to lift the ads?