Usually when it comes to Atari 2600 ports from the arcade there's usually a lot of compromises that have to be made in order for the game to even be mfin legible, let alone carry the same game feel. Luckily for Atari, Space Invaders is a game so popular and simple that it can make the jump with primarily frivolous changes.
The core gameplay here is the same space invading as it always has been. Only one shot from your guy can appear on-screen, waves of invaders coming down that increase in speed as their numbers fall, blocks to hide behind, if they reach the bottom it's game over, a bonus ship comes by periodically for extra points, yadda yadda. Some primary changes from the arcade include the fact that the ship can't move entirely across the screen on both sides which makes prioritizing the right side way more important than the left, the number of invaders per level has been cut from 5 rows of 11 invaders to 6 rows of 5 invaders, and the scoring is different between the two. The secret of hitting the bonus ship on the 23rd shot to get extra points is also entirely absent from this conversion, so score junkie shot-counters won't get much practice from playing this. They did add some interesting new game modes to shake things up though, such as the ability to make the game have any combination of moving shields, zigzagging enemy bullets, super speed enemy bullets (but no extra speed on yours because fuck you i guess), and invisible invaders. The moving shields and zigzagging bullets honestly give the game a bit of extra freshness, but the other two modes just feel too unfair against the player for me to have any sort of fun with em. There are also a ton of two player modes that are good fun with a friend. Each combination of modes is represented as its own distinct game number so there's 110 different game types you gotta flip through. Make sure to keep that manual handy to know which one is which!
While it definitely seems like the nuances between this game and the arcade version would make it pretty crummy for actual score practice at home, I don't really think that many people buying this in its time really cared about that kind of thing. The core game feel is close enough to the arcade that I'd say it's a good port. Hell, I bet most people didn't even notice there were differences and were just happy to play some space invaders without throwing endless quarters in a machine. It's no wonder this game wound up being the second best selling game on the system.
The core gameplay here is the same space invading as it always has been. Only one shot from your guy can appear on-screen, waves of invaders coming down that increase in speed as their numbers fall, blocks to hide behind, if they reach the bottom it's game over, a bonus ship comes by periodically for extra points, yadda yadda. Some primary changes from the arcade include the fact that the ship can't move entirely across the screen on both sides which makes prioritizing the right side way more important than the left, the number of invaders per level has been cut from 5 rows of 11 invaders to 6 rows of 5 invaders, and the scoring is different between the two. The secret of hitting the bonus ship on the 23rd shot to get extra points is also entirely absent from this conversion, so score junkie shot-counters won't get much practice from playing this. They did add some interesting new game modes to shake things up though, such as the ability to make the game have any combination of moving shields, zigzagging enemy bullets, super speed enemy bullets (but no extra speed on yours because fuck you i guess), and invisible invaders. The moving shields and zigzagging bullets honestly give the game a bit of extra freshness, but the other two modes just feel too unfair against the player for me to have any sort of fun with em. There are also a ton of two player modes that are good fun with a friend. Each combination of modes is represented as its own distinct game number so there's 110 different game types you gotta flip through. Make sure to keep that manual handy to know which one is which!
While it definitely seems like the nuances between this game and the arcade version would make it pretty crummy for actual score practice at home, I don't really think that many people buying this in its time really cared about that kind of thing. The core game feel is close enough to the arcade that I'd say it's a good port. Hell, I bet most people didn't even notice there were differences and were just happy to play some space invaders without throwing endless quarters in a machine. It's no wonder this game wound up being the second best selling game on the system.