Steal An Egg wiki: I pick the pet, no egg lottery.

Pick creature, aura and size, and watch the income per second stack from the game's own formula.

The wiki tells you what a pet earned. Start from the pet instead.

In the game you steal eggs, hatch them and hope for a rare pet, a good size or a mutation. Here the order flips: you choose the creature, the aura and the size, you watch its income per second build from base x aura x size, and you send it to your pen with your Roblox username.

Game facts on this page come from the game's own Roblox page, as it read when this page was written.²

pet-forge

your-pen

roblox-username: how it finds your account. Games give you a username and a password; only the username goes here.¹
security-check: one check, then the pet heads to your pen

where-it-runs

I hunt one exact pet

Then this is your shortcut. Start with the creature, set its aura and size, and send it to your pen.

I only compare pet values

The wiki tables handle that. When one pet stands out, return and build that one here.

I have not played Steal An Egg before

Hatch a few eggs in the game first. Once you have a pen of your own, the forge makes sense.

Set the creature, the aura and the size, and the pet heads to your pen.