777 Streak: Megacharged

Symbol Upgrade is a powerful feature that progressively converts low-value symbols on the reels into higher-value ones as the game proceeds. The core of this feature is not just a one-time symbol change, but a 'growth' structure where lower-tier symbols are permanently removed from the reels and replaced by higher-tier ones. This drastically increases the average expected payout of the reels towards the end of the round.

Ante Bet is a special betting mode where the player pays a small additional cost on top of their base bet to artificially increase the probability of entering the game's core bonus feature (usually free spins). It is a kind of 'strategic booster' offered to players who want to enjoy the highlight moments with a higher probability than a regular spin, but at a lower cost than directly buying the bonus game.