Getting back into Warframe was like riding a bike you never really forget. But as you play through the game and start to collect more and more Warframe and Weapons it soon becomes an addiction. I started out with only one frame when I came back to the game 213 days ago, I am currently missing 1 standard Warframe from a planet and around 8 in total. This is good considering some players have never stopped playing and are still missing several. I also only have 3 Prime Warframes to collect (4 but will never get Excalibur Prime so don’t count that one). Collecting the weapons is probably the hardest part as late game most need forma and I play daily and rarely get one a week.
There is also other materials like Nitain Extract which is an alert dropped which usually comes once every 5 hours. The hardest to collect is Argon Crystals which only stays in your inventory for a short period of time, you will lose one every 24 hours (I think or all in 24h). It used to drop maybe one in a void run but lately I have been doing a 20 minute survival and getting 5+ with this happening I have been doing a void survival run every time I need some. Not sure if it is a glitch but will soon see as DE patch these things often to help with the longevity of the game.