"Metroidvania" is a term used to describe a sort of exploratory 2D platforming game. It comes from the original games of the Metroid series and some of the middle-era of Castlevania games (most notably "Symphony of the Night", which is what primarily gave birth to the term).
The most defining feature is usually the world. Rather than have set stages or a world map, the entire game takes place inside one giant map, which you must traverse about. Not just any map, but typically a very complex map filled with all kinds of secrets. The map is typically divided into sectors, more in an aesthetic fashion to denote that the denizens and dangers will be different. Sometimes you have teleports to assist you in travel, but other times you just have to remember where to go in the map.
There's various elements at play in the exploration. There's typically tidbits hidden in spots, or puzzles that have to be returned to when you find appropriate equipment. The exploration is also non-linear - your limits of progression through the map are by various tools or powerups that you need to acquire, but the order in which you must acquire some of these tools is not set. And in many choices, there are many paths to get those tools, or even get past obstacles without those tools.
A very popular element of these games, especially in the Metroid franchise, is the concept of "sequence breaking". Using special tricks or otherwise mastering the utility of your basic abilities, you can sometimes access items and areas far earlier than the game expects you to.
As far as I know, Metroidvania games have always been 2D platforming games. Aside from the elements of exploration, the actual gameplay of Metroidvania games vary widely.
Aggro-deck is a term borrowed from games like Magic the Gathering. It means a deck that intends to play aggressively and kill your opponent as quickly as possible.
An aggro deck in Hearthstone is characterized by the following:
- Low mana curve (allows you to play many cards quickly)
- Aggressive creatures (high power relative to toughness) with abilities like charge, battlecry, overload and stealth
- Direct damage (burn) spells
Forcing the opponent to attack your minions with taunt rather than your hero is not a primary characteristic of aggro decks, because an aggro deck will not worry about taking damage since it is going to kill you before you kill them. An aggro deck will typically avoid playing taunt cards because the player is choosing to sacrifice defensive power for offensive strength.
Some cards that would fit the classic "aggro deck" include lava burst, reckless rocketeer, unleash the hounds, and nightblade. These cards fit because they focus on dealing as much damage to the opponent as quickly as possible, and have an effect the turn they enter the battlefield.
The opposite of an aggro deck is a control deck, which is a deck focused on removal and counters, defenses, cards that get stronger over time, and keeping a full hand of cards.
Cards that are neither aggro nor control can be referred to as "midrange" decks. Those focus on cards that are extremely efficient.
Best Answer
A rail shooter is a shooter game in which you don't have control over your movement, at least for the most part. The movement of the character is pre-determined, although some rail shooters will give you some movement control. Although this normally amounts to nothing more then choosing which path to take.
Resident Evil Umbrella Chronicles is a prime example of this: