There are various mobile games featuring UFO Robot Grendizer (often spelled Grindizer in different regions).
Go to Settings > Security (or Apps ) and toggle on "Install Unknown Apps" for your mobile browser or file manager. Download Asm Grindizer apk
A typical informational guide is usually between 15 MB and 55 MB . If the file is significantly larger (300MB+), it is likely a high-graphics game. Did you mean a specific Grendizer game, or There are various mobile games featuring UFO Robot