How can I check if the user is playing the game for the first time? - unity3d

Question

I want to show a text for the first time running like "Hi, my name is NAVI." and then when the player will start the game again the next time it will another text for example "Welcome back."

Answer 1

Using player prefs is probably the easiest solution, though definitely not the only one*.
Due to the lack of boolean playerpref I usually opt to use SetInt/GetInt instead, but that's personal preference. You could also do it with a string or float.
private void Start()
{
if(PlayerPrefs.GetInt("HasLaunched", 0) == 0)//Game hasn't launched before. 0 is the default value if the player pref doesn't exist yet.
{
//Code to display your first time text
}
else
{
//Code to show the returning user's text.
}
PlayerPrefs.SetInt("HasLaunched", 1); //Set to 1, so we know the user has been here before
}
Playerpref stores values between sessions, so the next session will still have "HasLaunched" set to 1. This is however stored on the local device. so users can manually reset it if they'd really want to.
If you ever want to show the "first launch" text again, simply set HasLaunched back to zero, or delete it altogether with DeleteKey("HasLaunched");
*There are plenty of alternative solutions, like storing it in a config file locally, or using a remote database (this would be required if you don't want users to be able to reset it). They would however come down to the same principle. Setting a value to true or 1 somewhere, and checking that value on launch.