Escape Velocity Space Shooter is a top down procedurally generated space shooter that is free to play but includes in app purchases that range from $0.99 - $9.26 per item.
Ranked in these QuestionsQuestion Ranking
Pro Loot system
Somewhat like a roguelite, there is a loot system that helps the player upgrade their ships in order to get further in the game. Once the player dies (which happens often) they use the loot collected to upgrade to then try again and get a little further and collect a little more loot.
Pro Procedurally generated gameplay
Every playthrough is procedurally generated, making for a unique experience every time.
Con Difficult at first
Starting the game is a bit rough before one upgrades their equipment.