Vowel Space Travel app
This game was made for you to explore British English vowels and to learn to perceive them better. Each vowel is a planet and you travel through a galaxy of these planets, trying to hear the differences between the vowels in different words and learning to do that better.
You will discover that hearing the difference between two vowels will sometimes be easy and sometimes more difficult. So you can find out which vowels you need to work on, and focus on them. A native speaker of Spanish may end up on missions in a different part of vowel space from a native speaker of Japanese. Native speakers of other varieties of English can have a go at distinguishing among the vowels of British English.
Vowel Space Travel is available for free in the App Store.