Problems with Huawei Phone
As others have mentioned in the comments, 512 MB RAM with 30-40 MB free might be insufficient for running newer, resource-hungry games.  Your version of Android (4.1, according to Huawei g520-5000's specifications) already handles memory quite efficiently by terminating background apps when more RAM is required for games and such.

Your best bet would be contacting the game developers over e-mail and asking for help.  Many will provide some support, just be prepared to know how to extract and send over the phone's logs.  Some, such as Vector Unit (developer of Riptide GP2) even go as far as issue a refund if they can't help you with the problem:

Quote from Riptide GP2's Play Store description:


  • • CUSTOMER SUPPORT • •
  If you encounter a problem running the game,
  please email the device you're using, Android OS version, and a
  detailed description of your problem to support@vectorunit.com.
  We GUARANTEE if we can't fix your problem we'll give you a refund. But we
  can't help you if you just leave your problem in a review.
  For fastest support on most common issues please visit: www.vectorunit.com/support