Los Sims™ FreePlay2011

Premium currency

You do not pay in euros, you pay in gems, so you lose track of the real cost.

Evidence: Wikipedia (es): «Además, hizo énfasis en el sistema de microtransacciones y el uso del tiempo real como parámetro en el juego.»

Paid loot boxes

You pay without knowing what you get. The good stuff is rare, so you pay again and again.

Evidence: 1 producto(s) a la venta, p. ej. «Caja de puntos de vida»

Interstitial ads

Interrupts play with ads.

Evidence: la ficha declara que contiene anuncios

Sold in parts

The full game costs more than the price on the box: there is separate paid content. Not a dirty trick, but worth knowing before buying.

Evidence: Wikipedia (en): «=== Downloadable content === ==== Pre-order content and The Sims 2 Store ==== Most of expansion packs and stuff packs were released with pre-order items.»