REDU format ruling
UFOroid

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)When this card is destroyed by battle and sent to the Graveyard, you can Special Summon 1 Machine-Type monster with 1500 or less ATK from your Deck in face-up Attack Position.
Rulings
- If "UFOroid" attacks an Attack Position "Pyramid Turtle", first the turn player decides whether to activate the effect of "UFOroid" or not, and if he does, it will be Chain Link 1. If he doesn’t, the opponent has a chance to activate "Pyramid Turtle’s" effect and be Chain Link 1. If he does, it is too late for the turn player to decide to activate "UFOroid’s" effect.
- If you do not choose to Special Summon a Machine, this card’s effect will not activate or start a chain.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.