I'm creating a 2d sidescroller beat'em up game and wanted to know what separates the good beat'em games that are fun and have replayability from the brain dead games where all you do is spam the attack button to win.

I am going to list what I think separates a good game of this genre from the bad ones.

1. Need at least two buttons: one to punch, one to block.
2. have enemies that give you a reason to block.
3. putting in different attack combos
4. variation of enemy types (ex. high damage, high health)

I want to know if these are good ideas as well as any other ideas or concepts that I might have missed.

If you think there are better ideas put them down below.

I think that what separates good beat'em games from bad ones (and not only beat'em, in fact) is strategy. In bad game, you just mash buttons / hold the FIRE button / whatever, but in good ones, you have to think (if only subconsciously). What is this enemy's strategy? How can I avoid his blows? What strategy should I use to defeat him?

Force a pause between blows, so a button masher does minimal damage. Make the enemy do attacks that cannot be blocked, so the player is forced to move. And make each type of enemy move according to some set of tactics (that can be even randomized a little if you are unforgiving). Be creative and make the tactics of every type of enemy different. The player may lose a few times, but he must learn. That way, a victory will be much sweeter, brought with blood and tears, than an easy one.

I don't think that your list must apply in every case; it is the standard of the current beat'em ups, but it is not the "holy grail". Experiment and find what you like.

Interesting, I like your ideas of pauses needed between attacks as well as unblockable attacks. With the idea of strategy, I feel that the distinction between playing offensively and defensively also plays a major role in that sweat victory. But would the inclusion of more attacks (lets say kicking) different speed of attacks (powerful attacks require more time then smaller attacks) add more to the experience or make it overly complicated?

Also concerning enemy health, would having an equal mix of weak enemies and strong enemies be better to have then lets say consistently stronger enemies as it gets harder (basically having no weak enemies)?

Though harder work yields greater rewards wouldn't the persistent difficulty make it frustrating if the player is unable to overcome the obstacles?

I think what you're getting at is pacing, and good pacing can make a good game great or an otherwise fine game tedious.

Pacing can, and I think should, be achieved in ways other than the numbers inherent to an enemy though, as ifthen touched on. You're right, a linear increase in difficulty can and often will frustrate the player, especially if the playable characters are supposed to be getting more powerful. Nothing takes the fun out of getting power-up or level or weapon than having an enemy that just gets stronger right back at you. I think Diablo 3 is a good example of how this was done wrong.

So, how do you make the game harder while getting your players to keep playing? How about different battle-types: maybe in one encounter your player is put in the defensive position, avoiding powerful attacks and really trying to time their offensive moves well so that they don't get hit in the process, while in another your character is chasing a set of enemies around the screen while they run away and fling rocks in your direction. There are a lot of ways to vary the types of encounters your player will face beyond making enemies that have different dps/hp ratios, and your players will thank you for supplying them.

Question on making the game difficulty scale when acquiring new abilities; Would making the game be really easy in the beginning of the level and then scale the difficulty as you progress later in the level maybe a better option?

My logic behind this is that the player would still be able to feel powerful after receiving the new powerup in the beginning and would not feel any frustration, but the level difficulty would still be there and in the end make it feel like a more balanced feel.

That is a good point for putting foes that where once hard but now easier. But one question for the parry. Would it be acceptable to make a parry a button combination like making the player press the attack and block button at the same time or it should have its own special button?