It's time to return to Aperture Science for some totally not deadly tests. Note: this assessment of deadliness is not guaranteed. There may actually be a great deal of danger, depending on your construction abilities. GLaDOS will be your guide as you take on your role as bridge builder in this fusion of Portal and the Bridge Builder games, and GLaDOS is not so good at keeping people alive, either.
The gameplay is more similar to Bridge Constructor than Portal, which should come as no surprise. Your goal is still to build bridges and platforms in order to allow test vehicles to make it to the exit. However, this time there are hazards of a more "scientific" nature like lasers and pools of acid. You know, typical science stuff. Also, there are portals. Like in Portal and Portal 2, you leave a portal at the same speed you entered, so you have to plan ahead and take advantage of physics.
There's plenty of clever dialog in the style of Portal, and Ellen McLain is back as the voice of GLaDOS. This game costs a mere $4.99 with 60 levels, and there are no in-app purchases.