There is a topic above called Dark Heresy that implements the Magic System as Psyker powers.

I love the genesys magic system but if you just wanted those 2 powers you could consider using some of the force powers from the starwars line. If you limit that system to a set amount of force rating it will not get 2 out of hand. Since each power has its own tree with xp cost players still have a choice on what to get.

Consider using both skills and talents, where the actual use of the power is through talents, but the size of the effect is equal to ranks in skills.

2 minutes ago, TheSapient said:

Consider using both skills and talents, where the actual use of the power is through talents, but the size of the effect is equal to ranks in skills.

Yeah, a level 2 or 3 talent that allows the power then uses a Discipline check to use. You could even have Improved and Supreme levels to flesh it out some more.

I'm working on a similar idea myself (a Psionics Supplement for Shadow of the Beanstalk).

Currently I am inclined to treat Telepathy and Telekinesis as willpower-based skills. Access will be limited to characters of the appropriate archetype or career, and those who purchase the "Late Bloomer" talent. Buying a rank in either skill unlocks the most basic power associated with the skill, but the more advanced powers would be organized into power-trees (rather than using the Talent Pyramid). You would simply pay XP to develop any given power (or modifier) whose direct prerequisites you met. Ranked powers/modifiers would increase in cost (just like ranked talents).

Naturally, there would be some associated Talents as well (like Late Bloomer), but they wouldn't be the meat of the system.

For the telepathic powers, I'm using the Psionic powers from the GCRB as examples, but I'm also going to steal several ideas from the Hero System and FFG's Star Wars line. Genesys Superheroes by @IndianaWalsh also deserves mention as an invaluable reference.

Most telepathic powers will involve performing an opposed Telepathy Vs. Discipline check to cause a given effect (examples include Mind Control, Mind Reading, and Mental Illusions). Those that function as combat checks (such as Mental Blast) will naturally use those rules as appropriate. Likewise powers without particular targets (such as Mind Scan) will have set difficulties. Finally, some powers won't require a check to activate (like Mind Speach), and a rare few'll even be passive (like Mind Ward). Telepathic powers will initially have a Short maximum range, and 'Increased Telepathic Range' will most likely be a Tier 3 Ranked Talent which increases the maximum range of all Telepathic powers by one Range Band.

Some powers will have optional permutations which can be developed (e.g. Mind Scan into Mind Search); these will usually provide an additional or modified effect in exchange for increased Difficulty (much like the Magic system) or costing Strain. Other powers will have entirely different effects, but which represent a logical and thematic progression (e.g. Mind Reader -> Mind Shaper -> Mind Control).

Only a few of my psionic powers will cost Strain to activate, because unlike the Magic Skills, Psionic Skills won't provide significant benefits by themselves. Instead, the majority of your 'spells' cost extra XP to develop. For example, having ranks in Telepathy might only grant Mind Speach (which doesn't even require a check).