Wording is anatomy, not style
Most invitation messages fail for a boring reason. The date sits in the first line, the venue turns up three messages later, and the ask is buried under a paragraph of apologies. Guests do not read; they scan. Your job is to give the scanning eye something to find.
The five parts never change, whatever the tone. What is happening. When it starts. Where it is. By when a reply helps. And one link that carries everything else. Once that skeleton feels automatic, the wording can be playful, formal or plain. Structure first, voice second.
Here is the part that surprises people: you no longer have to pack the address, the schedule and the dress code into the chat. Those live on the page the link opens. The message earns the tap; the page does the explaining.