Usernames built from an adjective and a noun, in the four shapes gaming platforms actually accept, including the digits you add when it is taken.
Platforms disagree about what a username may contain, and the four styles here map onto those rules. CamelCase is the safest: letters only, no separator, accepted everywhere including the strictest game clients. Snake case with an underscore works on Discord, Steam and most launchers but is rejected by several console platforms that allow no punctuation at all. Leetspeak substitutes digits for letters, which is the standard way to claim a name whose plain spelling is long gone. The clan wrapper with decorative x characters suits a display name rather than an account ID, since many login fields will not take it.
Appending two digits looks lazy and is actually the most reliable move on any platform with a global namespace. Every memorable adjective-noun pair was claimed years ago on the large platforms, so a bare tag is almost certainly taken, and the alternative to digits is misspelling the word, which costs you the readability that made the name good. Two trailing digits keep the name pronounceable and searchable while giving you a hundred variations of the same idea. Check the length limit before you commit: Xbox allows twelve characters, Discord thirty-two, and most game clients sit somewhere between.
CamelCase. It is letters only with no separator, so it passes even the strictest console and game-client rules that reject underscores and symbols.
Because good adjective-noun pairs are long claimed on large platforms. Two digits keep the name readable while giving you a hundred variants to try.
Usually not. The decorative wrapper is for a display name. Most account fields reject the spacing and symbols it uses.