EDIT: Don't know why I thought you wanted this for IOS - must have been reading something else. Please ignore if you do not.

ON IOS

You have to modify the XCode project to achieve this and add a entry to the info.plist plus handle the code on app launching.

This defines a URL scheme for radicalWords which you use in a link as radicalWords://someparameters

The following is at the bottom of my info.plist just before the last tag

    <key>CFBundleURLTypes</key>    
    <array>
     
     <dict>
         
         <key>CFBundleURLName</key>
         
         <string></string>
         
         <key>CFBundleURLSchemes</key>
         
         <array>
             
             <string>radicalWords</string>
             
         </array>
         
     </dict>
     
 </array>

Then you need to register your own app controller to take the initial parameters - this is achieved by putting the definition in Plugins/IOS in your project - I'll list it at the bottom. My version calls a method on a game object called !URLSchemeHandler (which must be available in the first scene) - the method is OnOpenWithUrl and it takes a string parameter of the url passed in which I then parse in C#.

MyAppController.m

 #import <UIKit/UIKit.h>
 #import "UnityAppController.h"
 
 @interface MyAppController : UnityAppController
 {
 }
 
 - (BOOL)application:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions;
 
 - (void) openURLAfterDelay:(NSURL*) url;
 
 -(BOOL) application:(UIApplication *)application handleOpenURL:(NSURL *)url;
 
 -(BOOL) application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation;
 
 @end
 @implementation MyAppController
 
 - (BOOL)application:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions
 {
     [super application:application didFinishLaunchingWithOptions:launchOptions];
     
     if ([launchOptions objectForKey:UIApplicationLaunchOptionsURLKey]) {
         NSURL *url = [launchOptions objectForKey:UIApplicationLaunchOptionsURLKey];
         
         [self performSelector:@selector(openURLAfterDelay:) withObject:url afterDelay:2];
     }
 
     return YES;
 }
 
 - (void) openURLAfterDelay:(NSURL*) url
 {
     
     UnitySendMessage("!URLSchemeHandler", "OnOpenWithUrl", [[url absoluteString] UTF8String]);
 }
 
 -(BOOL) application:(UIApplication *)application handleOpenURL:(NSURL *)url
 {
     
     UnitySendMessage("!URLSchemeHandler", "OnOpenWithUrl", [[url absoluteString] UTF8String]);
     
     return YES;
     
 }
 
 
 -(BOOL) application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation
 
 {
     UnitySendMessage("!URLSchemeHandler", "OnOpenWithUrl", [[url absoluteString] UTF8String]);
     return YES;
     
 }
 @end
 
 
 
 IMPL_APP_CONTROLLER_SUBCLASS(MyAppController)